I went with a MOTU 8pre for my Mac setup. Has always worked really well. I love it.
I had a Presonus FireStudio and after years of major issues and not being able to even USE it :x Guitar Center finally gave me store credit to get a MOTU instead. For some reason I got a lot of "hiss" through it and everything sounded distorted, like I had the gain cranked. I had Guitar Center's extended warranty, so I kept sending it out for repairs... it'd be gone for months, then they'd send it back saying it was fine, and it'd still have the "hiss" and high-gain sound. Not saying that Presonus is a bad option to go with... I believe I just had a lemon... but I was certainly fed up with them at the time and the MOTU was an awesome replacement.