OctaCapture on Win 10 with Sonar Plat.  Never a glitch.

Emu 1820 :) rock solid! (sonar platinum, win 8.1)

Rob, I'm retired and I just bought the Motu 24AO, after years using two Delta LT1010 cards. I thought I could use the LT1010 cards for the input, but I found out you can't use two ASIO devices at the same time, you have to switch to one or the other in Cakewalk. So I then bought a Behringer ADA8200 the newer version of the ADA8000. It gives me 8 inputs via ADAT lightpipe which goes into my 24AO and I use the 24AO as the master clock to the ADA8200 via a BNC cable. If you can clock 2 Behringers' ADA 8200 together (16 in) for $400 and use a Motu 24AO $995 (I used a coupon on musicians friend and saved almost $100) We are talking $1300 vs buying a Motu 24IO $2000~. Add 2 optical cables, 2 BNC connectors, plus the analog cables. 

I see some folks using UA Apollos. I thought they were Thunderbolt and/or Mac only?? If so, how are you making them work on a PC?

I run 2 Lynx AE16e cards on the same machine using ASIO. Low latency and stability. I had the PCI cards before and the Lynx have been incredibly stable. Something I could never say about the MOTU 2408s that they replaced. Granted, you still have to buy converters (I have 8 channels of Mytek, 8 channel Lynx Aurora and a 16 channel Lynx Aurora). I can record 32 tracks at 192k without any issues. I could not be happier.

I have a Quad Capture, the sound quality is brilliant... but the lack of a headphones switch is a pain. 
 
I looked into getting an Octa Capture, but it has the same preamps as my existing Quad Capture i.e. a very expensive upgrade for little benefit. Now if Roland are about to release a new version of the Octa Capture with say USB3 support, then that would tempt me. 
 
In the meantime I've had my eyes on the new Focusrite clarett 4pre... but it will require a Thunderbolt expansion card and is currently Mac only. They are apparently working on Windows drivers, but it's harder to get them certified on Thunderbolt. 
 
~ Tony

So far the Motu 24AO which I have going into 24 channels of my mixer has been great. I had to adjust the communications settings to be quicker, because after I played back a previous project using 16 channels with multi instruments, it dropped out. But I've never hear any noises or ticks like I did with my 2 Delta 1010Lt cards. But to be fair, M-Audio did not recommend multi 1010LT cards with their Win7 drivers. With the 24AO, when adding audio on those previous projects through the Behringer ADA8200, it has been perfect in sound and timing. As far as latency, if I use my midi or keyboards, I don't hear any, it's perfect to my touch. The only problem I've found so far, when recording a new midi track, there is quite a delay in the playback only, and I had to set the playback midi + delay real high value on the midi playback timing in Platinum, it's really behind. After making those adjustments, I was surprised it didn't affect my audio or previous midi recordings. Also after I've got the 24A0, it automatically loaded everything from the net. but then stopped being recognized once I started Cakewalk. I then switched the USB cable from my USB 3.0 to USB 2.0 connector, and haven't had a connectivity problem since. I used the USB 3.0 connector at first, thinking the higher bandwidth would be better. Right now I'm 99% confident I wont have any more hardware problems, midi or audio, recording or playback. First time I can say that in years. Whatever you do I hope it works for you. My hardware problems were taking the fun out of making music. Been using Cakewalk since Cakewalk DOS.    

At this point, I'm leaning toward a Focusrite Sapphire Pro 40 with a Focusrite Octapre MkII Dynamic. It seems that a lot of people like this setup and, I found out a local friend of mine is using this setup with Sonar and is loving it.
This would seem to do what I need (16 channels), at a reasonable price. In fact, I could save even more money by going with the standard Octapre instead of the Octapre Dynamic.
If my budget were larger, that might change everything, of course. The Pro 40/Octapre, though, seems like a good, cost effective solution and, one that a lot of people are quite happy with. 
Regardless of what I end up with, I love seeing what everybody else is using. Personally, I feel like there's not enough real information out there to help guide people on an interface purchase. This has been very helpful to me and, I hope to others. Thanks everyone for your responses!
Oh, and, feel free to keep the responses coming.... I haven't actually bought anything yet and, maybe it will be helpful to others, as well.

Edirol UA25, later called Cakewalk UA25 (!) perfectly stable and with great preamps. If I had to change it now I would go for Zoom UAC2, very good preamps and comes with USB 3.0

4 each M-Audio Octanes connected to my 16 year old Sonorus/Montana cards, works OK with the beta drivers under Win7 on my 4GHz 6 core i7-3930K DAW.

Bought a RM32AI almost a year ago and it's been gathering dust while I work my tail off on the day job. But, now that gigging is a wrap for the summer I intend to promote it more than just paperweight status. :-) It's going to replace 3 mixers and a rack full of gear!

I've been very happy with the gig recordings from my 16.4.2, and I think the RM32AI pres sound even better.