The best fender depends on the bike (and the use). For road/hybrid/city/roadster etc. I'd pick SKS for "narrower" tires and PB Cascadia for wider tires. Do consider the Velo-Orange mentioned above. Now that they are pre-drilled they are at least as easy to mount as the others -- and they offer better coverage (they wrap more of the wheel). Any of the three should do a good job - just leave enough clearance for mud or snow or ice or whatever shows up in your area.