I own a CZ 75B, SIG 229 (in .40) and a 9mm SIG 226. I used to own a CZ 40B. My best friend has a CZ 85Combat (which I have shot fairly often). So, I know a little about both.
All else being equal, I'd buy a SIG over a CZ any day.
Reliability goes to SIG hands down.
My CZ 75B has been mostly reliable, but I have had some bobbles over the years (about one every 500-1000 rounds so not terrible). Overall it is decently reliable, but my friend's 85 Combat has been fairly bad and another friend (an online pen pal) had a ton of trouble with two CZ 75B's (CZ couldn't fix the first one and replaced it and they never got the second one right either but it was OK- just not good enough for him to trust as anything more serious than a range gun). My CZ 40B was a reliable gun. So, of the 5 guns I know 2 CZs were good (one with some problems, but reliable enough for HD/CCW if needed), 1 has been junk (replaced by CZ) and 2 were OK to trouble (but not enough to return it). I don't rate CZs as unreliable because my personal experience is decent, and there are plenty of positive reports online, but it isn't hard to find reports of trouble either.
My SIG 226 did have a few problems when I first got it, but it was quickly fixed and has been 100% for most of the time I've owned it. I chalk the issues up to my learning curve. It does not like running dry- I simply switched from a VERY light coat of oil to a heavier coat of oil or a light coat of grease and have had 0 problems since. I bought my SIG 229 after I knew better and I've never run it dry and it has been 100%.
Fit and finish, the SIG has it all over the CZ. If you look at the machining work inside the guns it is night and day. Outside, the CZ looks good.
Feel...there is a subjective difference in feel between an OK to good gun (CZ) and a great gun (SIG). Hold them, pull the trigger (when they have the same manual of arms), take them apart if you are allowed to by the store, etc.
Ergonomics...this is very subjective so you will have to hold both and see which you prefer. The CZ may have it over the SIG, but I actually like the way my SIGs feel.
Accuracy...both are good. It is hard for me to tell which is better, I shoot the CZ a little better (and not by much). But then, I have well over 10K rounds through my CZ and only 1000-2000 out of each of my SIGs so I am just a bit more experienced with the CZ.
Looks..CZ all the way, but if that is your main criteria go with a Browning or FN HP, it will be a quality gun that looks great (much better than either the CZ or SIG).
Costs...Obviously the CZ is less, but not to the degree it used to be. CPO SIGs may not be much more than a CZ (of course, that is a used but factory reconditioned gun v. a new gun). If you can't quite afford the SIG and don't want a CPO then get the CZ. They are decent guns so you won't be going wrong. If you are comfortable with the price of a SIG (or don't mind a CPO) then get the SIG.
All that said, if you see some of my other threads you'll see that I'm probably selling my 226 and keeping my CZ, but don't read too much into it. I've had the CZ a long time and at times it has been one of my favorite guns, so even though I like the 226 more right now I don't want to give up an old workhorse. Also, the 226 will net me a lot more money as it is worth much more money. Last, if I sell the CZ I have no CZ (and I do like the platform) and I'm not sure I'll be buying any more CZs while if I sell the 226 I still have the 229 and I will be buying more SIGs in the future (including possibly a 226 in .40S&W).