I did a lot of research into this last fall when looking for a 13" brake kit. Each brake setup is different, and it depends what your goals are for the car... the info below is just my opinion.
Wilwood makes some outstanding brake kits, some of their kits fit under wheels better than other block-style calipers, but some of their calipers also don't have dust boots (which isn't recommended for street use). As already mentioned, they also offer a lot of cheaper drag race oriented kits that are undersized for a full weight street car. Their prices for a quality kit (6 piston front calipers) were comparable to or higher than the Baer sets I looked at, they would have cleared my front wheels, but didn't have dust boots.
Baer (Track 4) was going to be my preference due to their well-designed calipers, quality parts, etc... (all discussed above), but the calipers would not work with my wheels after I printed the templates. The price for what you get is great. However, I didn't want to have to change wheels at this point. The Baer small rotor kits are going to be significantly more powerful at stopping than the Wilwood thin rotors.
I ultimately ended up with brand new PBR C6 calipers and DBA 4000 series rotors with Hawk pads. It gave me the most wheel clearance and was also the most economical option. I would assume I gave up some braking performance to the Baer setup due to caliper rigidity, but it was the trade off I had to make.
What I'm getting at is: set the goals for your car (drag race, street, autocross, track), decide what you want to do with wheels, talk to suppliers, print templates, check fitment, and find out what works for you.
