Not to steal Craig's thunder w/ Tascam, but the new(ish) UH-7000 is pretty darn good.  Not the greatest low latency drivers - about 12 ms in/out on my system, but I haven't tried to tweak it either.  Other than the drivers, it is a really high-end unit.  Excellent conversion and stellar preamps.  Clean, but sweet.  I doubt if I'd pay $600 for conversion - it is better but not by hundreds of dollars.  Even budget converters are really good.  But combined w/ the preamps it is a really stout-sounding unit and you don't need external hardware to make recordings that play w/ the big boys.  No midi and stereo only, but it is very good.
 
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What you saying man? Focusrite is an amazing interface. You need to optimise your setup.

Alex yo have a saffire  that's not the same as the scarlett series. The scarlett's are entry level and have ho hum entry level performance. Read the bench tests.. Hidden buffers and all that.. For the money they are still a great choice. But good interfaces are still way up there in price. 
 
AT -I just checked the Tascam UH 7000 out and It look pretty impressive. I'd buy that just for the pre amps!  I will say I have no complaints about my us1641 other than the drivers, The rest of it hardware wise is well built and it sounds better than I was expecting. It just don't work well with Sonar. So I use it with Wave lab and a computer I have set up for mastering and playing as our home movies and stereo system. I will also use it if I need to go out and record a band. 

A very satisfied, Scarlett 18i20 user here. Nice preamps and rock solid performance for almost a year now. Highly recommended.

18i20 user here. Very satisfied. If you need plenty of inputs and outputs I can't fault it.

Thanks for the info guys. Drivers that work well with Sonar and latency are my main concern. What has your experience been regarding drivers/latency with Sonar?

I use my Joe Meek preamps and since I don't do live drums anymore, I guess I don't need 8 preamps any longer. I really like my UX8, but the drivers are crap and I'm fed up.

I use a lot of soft synths combined with audio tracks and haven't had any issues with drivers or latency in my system. I also have to say that Focusrite support is stellar which for me is another consideration when purchasing a piece of equipment. 

If you don't need the input count you might want to put your money into quality over quantity. 
Your pick of two interfaces are both entry level series for those brands that have a more inputs than you possibly need. 
Lower your input count and go to the next level and look at the Tascam UH 7000 ( like AT posted) and the Safire Pro series for the Focusrite. Then I would be looking at RME's basic models.  
If all you need is 2 or 4 inputs don't spend your cash on 8 pre amps. Spend it on  better components and A/D
 
Make a list of all the features you need first. 
 
How many Pre amps
How many Line ins
How many Instrument ins
How many outputs , do they need to be balanced
How many Headphone outs
Insert jacks
Are there easy to use front panel controls for all the above or is it software driven. Important! 
Does it have DSP for adding effects or compression.
SPDIF in and out   ADAT
MIDI 
Buss Powered ( this can cause issues with some systems ) or wall power ( better) 
On Off switch 
Metal or plastic case
Size is important for travel ( the UT 7000 looks way to big for me) 
 
Has it been bench tested for Round Trip latency and does this really matter to you. 
And are the drivers reported to be working well with Sonar and the OS you have. 
 

Thanks for all the info. This is getting interesting. Has anyone tried this one?
STUDIO-CAPTURE USB 2.0 Audio Interface

 

Hmmm, this one is really calling out to me!!!!!!!!!!!!!!!!!!
 
http://www.motu.com/products/motuaudio/896mk3