As others have said, it is best to get an idea of how much money you want to spend and how much you intend to sell professionally.  If the latter, you need to spend a little more because there is always some little twit thinking that x y or z brand is necessary.  Otherwise you spend the first part of any session explaining your system to some one that doesn't know anything but the adds they've read in a magazine but is sure that is what they need.
 
If for your personal use, you have a lot more leeway as long as you realize finding a single interface w/ 16 ins/outs is costly - most of those are made for professional studios.  Lynx comes to mind, tho at a more reasonable price the new MOTO line might fit your bill.  What you most likely have to do is find an 8 X 8 interface w/ ADAT expansion (ADAT being a digital in/out format).  You can spend a couple of hundred dollars on an 8 X 8 preamp and converter (Behringer) to closer to $1000 (Presonus) and over (Audient).  These are separate hardware units that simply plug into your interface and expand your system.   another route is stacking, whereby units from the same company can aggregate together (something ASIO drivers don't normally do).  So 2 8 X 8 units double your fun.
 
My own set up includes a TC Konnekt 48 which has 4 preamps, 8 additional line inputs, spidf and ADAT in/outs.  You can stack the whole family, tho I haven't tried it.  The hardware is superb, conversion is very good and preamps good and it comes w/ some great DSP (including reverb from the TC 4000).  It is cheap considering the quality since the original drivers were horrible and the reputation never recovered.  The drivers are fixed now but it can still be found for $1000 any day - and I got mine at less than that. It would be easy to add preamps from a mixer for the line inputs, getting close to your requirements before counting the digital ins.  I use mine w/ a Tascam UH-7000 hooked up via spdif - the 7000 is a new high end preamp/converter that I use as my main converters and for overdubs.  (Tascam has some new, budget units out that might fit your requirements and they are part of the Gibson family with Cakewalk).
 
It is good to get other people's opinion.  And read the mags.  But until you get a budget (esp. top line) it is hard to make recommendations.  Just remember that every extra dollar you spend on an interface will end up costing more than that to take advantage of it.  Better converters need a better room, mic and monitors to use them to their best advantage.  And better converters don't necessarily mean a better end product until you learn how to use them.  And even then, likely hood of your audience hearing the difference is small.  So buy the best you can afford and learn to use it.
 
@

AT-Good advice.....My final product is for albums, so the quality has to be there. I'm working on my 3rd album now. The first 2 were recorded and mixed on the Roland and they sound great. As BlixYZ was saying, a lot more goes into a recording besides various gear. I used good mics, I used Blue Tube preamps to warm the tone, I didn't overdrive the inputs (like you used to be able to do with analog...hehe), and the song material and the musicians were solid. I can't imagine that the difference in the signal is all that different from the cheaper interfaces to the expensive ones. Besides, if there are differences, can a human ear hear it? Compatibility, ease of use and additional features seem to be the important distinguishing differences. 
I'm currently leaning towards the Tascam....same parent company as Sonar, I've had lots of Tascam products over the years and they seem solid, and they work with USB 2 or 3. Still, I'm going to look at them all very closely before I decide. Thanks a bunch!

The sound quality of Tascam equipment has always been excellent for the money in the 35 years I've been using their gear. I like brands that have staying power like Tascam and Yamaha. All that gear still keeps going just like the energizer bunny.
 
Tascam had issues with using 3rd party ASIO divers and are now reported to be writing their own in house now. Focusrite has been the golden boy interface for the last year or so, I think with improved drivers Tascam will give Focusrite a run for the money now. 
 
Did you check all suppliers for the Tascam? I just used that link so you'd get an idea.
 

johnny V,
agree....i was just reminiscing about some of their gear i've owned over the years....
and even that m-50 board i used for so long....their preamps had a bad rap, but i always loved that board....i gave it to my little brother years ago when i went digital, and it's still working great...i still have one of their 2 track reel-to-reel machines....the drive needs repair, but i used to run the **** out of that thing....i'll have it fixed....
i still use my tascam cd-rw5000...it's a high quality cd recorder.....i used to take that to gigs and just plug a couple ksm-137's in and i'd get great recordings of the band....good for mixdowns too, even though obsolete...
 
astrumur

Astrumur. I can't imagine that the difference in the signal is all that different from the cheaper interfaces to the expensive ones.

 
The difference isn't simply in the analogue/digital convertors (in fact many interfaces use the same chips) but in their mic and line pre-amps and the circuitry that surrounds them. Higher end interfaces generally have a much lower noise floor than cheaper ones, though like anything else you do get diminishing returns above a certain price point. If you're recording and mixing a lot of tracks then 6dB |(or even 3dB) less noise per track can make quite a lot of difference to the end result. The other advantage tends to be better drivers, with implications for latency, and better (or more feature-equipped) firmware, software mixers/control applications and, often, manufacturer support.
 
Whatever, any decent audio interface with solid ASIO drivers will outdo a PC's built-in sound with ease and turn in workable results. I used a Cakewalk UA-101 for quite a while and it was fine apart from I badly needed more than 8 inputs, wanted lower latency, and eventually its USB socket started acting up. The RME does sound different, but not different enough to render my older mixes useless.
 
There actually aren't many interfaces with 16 or more inputs (I guess most people, especially at the consumer end of the market, mostly use software synths and just don't need them), hence the use of ADAT to digitally connect additional units to increase the input/output count. ADAT's like MIDI or the C programming language - it's been around for ages, when invented did its job so well it became the "industry standard" and still does it so well it has never been rendered obselete.
 
As for RAM, my DAW PC does other stuff besides audio, particularly graphics and once in a while video. You could probably do fine with 8GB in a 64bit system unless you use sample libraries a lot in which case being able to load them into RAM rather than having them streamed from the disk is useful, I'm told. Mind you, RAM is pretty cheap these days and more is generally better as it reduces the chances of Windows having a swapping fit at a crucial moment.

Astrumur. I can't imagine that the difference in the signal is all that different from the cheaper interfaces to the expensive ones.

 
The difference isn't simply in the analogue/digital convertors (in fact many interfaces use the same chips) but in their mic and line pre-amps and the circuitry that surrounds them. Higher end interfaces generally have a much lower noise floor than cheaper ones, though like anything else you do get diminishing returns above a certain price point. If you're recording and mixing a lot of tracks then 6dB |(or even 3dB) less noise per track can make quite a lot of difference to the end result. The other advantage tends to be better drivers, with implications for latency, and better (or more feature-equipped) firmware, software mixers/control applications and, often, manufacturer support.
 
Whatever, any decent audio interface with solid ASIO drivers will outdo a PC's built-in sound with ease and turn in workable results. I used a Cakewalk UA-101 for quite a while and it was fine apart from I badly needed more than 8 inputs, wanted lower latency, and eventually its USB socket started acting up. The RME does sound different, but not different enough to render my older mixes useless.
 
There actually aren't many interfaces with 16 or more inputs (I guess most people, especially at the consumer end of the market, mostly use software synths and just don't need them), hence the use of ADAT to digitally connect additional units to increase the input/output count. ADAT's like MIDI or the C programming language - it's been around for ages, when invented did its job so well it became the "industry standard" and still does it so well it has never been rendered obselete.
 
As for RAM, my DAW PC does other stuff besides audio, particularly graphics and once in a while video. You could probably do fine with 8GB in a 64bit system unless you use sample libraries a lot in which case being able to load them into RAM rather than having them streamed from the disk is useful, I'm told. Mind you, RAM is pretty cheap these days and more is generally better as it reduces the chances of Windows having a swapping fit at a crucial moment.