Apogee and MOTU are the brands that I can recommend from personal experience.

Specific models depend entirely on your needed feature set and your wallet size.

RME fireface UC. A little bit more expensive than MOTU but much cheaper than Apogee.

I like RME and everybody seems to do (apart from the price)

I currently use an M-Audio FW1814 which served me well for many years but I'm trying to drive down the latency: I can't play my funky guitar parts through this interface and I miss playing them live.

I use up to 4 inputs but never at the same time (bass, keys, guitar, mic) - I'm considering getting an RME babyface + a small mixer and just record everything through the same input. I also like that it will be a lot smaller and lighter in my backpack.  Still I'm not sure, it's a lot of money

Did you see this ? http://www.audiosolutions.fr/product_info.php?cPath=2_19&products_id=7072

thanks Stephane! I was not aware of that product, it looks interesting! Various reports though on the web about it's latency. I'm in a funny place: sound quality is not that important to me as I play live only (I don't record, or if I do I use nice preamps/converters I have at home) - latency is the main thing I worry about. Well and price, size and weight.

Bad experience with Apogee. No experience with MOTU.

Awesome experience with RME.

Latency == driver implementation. RME has better than the following I tried:

Mackie, Presonus, Echo, Apogee, Focusrite. Perhaps some other I forgot to mention...

Echo is close 2nd to RME. Everything else falls short...

I recommend EchoAudio Echo2 or RME Babyface for that type of thing...

I currently use FireFace 400.

Basvlk, I also had pretty good experiences latency-wise using an ageing motu 828 mk1 before my RME Fireface UC... Their drivers are also top notch.

Thanks Ploki - I read good things about M-Audio too - I do a lot of processing so I may not gain much from faster drivers if the main latency comes from processing on the CPU (mainly Ableton Live effect racks).. makes me think I should probably see how low I can get my M-Audio latency without any effects loaded: if it goes down to say 10 ms there's probably no point upgrading to RME or Echo

You have lower baseline latency with good drivers, so the processing you do just adds to that baseline, and the amount of it you can do also depends on stability of drivers.

In my opinion and experience M-Audio cards are not really good...

10ms is as much as you can hope for in this domain though. But 10ms is a lot.

It all boils down to Samples/Buffer. I can drive my RME 32samples/buffer via Firewire with no dropouts at all.

I could get my Echo down to 64samples/buffer but was not stable, Apogee also.

Mackie, Presonus, M-Audio; dare to dream going lower than 128...

Smaller buffer, higher sampling rate => lower latency.

RME have their own USB and FW drivers, while Apogee attaches to Apples generic Audio FW implementation.

hold on.. higher sampling rate = lower latency? I get that the buffer size responds to a smaller amount of ms with a higher sample rate, but it also make your CPU work harder.. I'd imagine a higher sample rate means you'll have to increase your buffer correspondingly.. well actually, let me just try it out at home :-)

Under 10ms is no issue for my MOTU 828mk2 firewire. Love it and served me perfectly for many years.

Got this bad intermittent crackle problem now though. Might be due to my hackintosh install but still haven't been able to check on a genuine mac whether it persists. Win7 on the same machine doesn't have it: https://cycling74.com/forums/audio-interface-acting-strange/

I've had the same thing happen on my MOTU microbook, and know other people who have reported similar problems (but with RME). It seems to happen for me when I hit a CPU usage spike.

I guess I should post this in the other thread...

I had a tiny bit of  time yesterday and found that in fact I can get roundtrip latency down to 7ms on my M-Audio FireWire 1814 so in fact it's not so bad at all! I tested it through a completely empty live set, with no plugins or anything.

note that this is the 'reported' latency in Ableton LIVE -which is not real-world latency. I suppose you all know http://www.dawbench.com/

so I'm changing my focus to the program, I'm going to add track by track back in and see how far I get without dropouts.

Still I have my eyes set on the babyface :-)

Rodrigo - probably unrelated, but my FireWire has very weird crackling noises which are often fixed after a reboot. the manual of course says you should shut down the computer, then connect the interface, and then power it up (but who shuts down their computer anymore?). It makes no sense to me how the interface works fine but with noise if you hot-plug it, but works quietly when you boot up the machine with the interface connected, but it does!