I've used:
- Ritchey Speedmax Delta
- Continental Cyclocross Plus
- Continental Race King
- Kenda Small Block 8
- Kenda Slant 6
- Kendal Kross Supreme
- Schwalbe Smart Sam
The Ritchey Speedmax is the best for mostly paved use. The continuous center tread rolls really well. It also has good intermediate tread (originally had "knob" here, but it's not technically a knob) so it handles consistently when cornering in the dirt. The Schwalbe Smart Sam would be my second favorite, except it has a big advantage-- you can get it in 40 and 45mm widths. (Ritchey's biggest is 35mm.) If you have the clearance, my opinion is that the 40 and 45mm tire rolls pretty well on pavement and the extra meat is a *big* advantage in the dirt. You can stop reading now, honestly, and just buy one of those two tires.
Pair them with Mr Tuffy Ultra Light liners if you live in an area with goathead thorns like me.
The Contis wear really fast and have small, very sparse knobs that are terrible on loose-over-hardpack. The Cyclocross Plus is also the heaviest cross tire I've ever used and yet it wasn't all that thornproof. I loved the 26x2.2" Race King but was really underwhelmed by the 700x35 version.
The Kenda Small Block 8 is a good all-around tire but it's very fragile. Expect a lot of thorns and if you get into big rocks expect a sidewall tear eventually. The Slant 6 is better offroad but the tread pattern kinda sucks on a 35mm cross tire. It works well on the 29x2 and larger. I wouldn't recommend the Kenda Kross Supreme in any conditions. It has tall, sparse, soft knobs that really suck on pavement and hardpack... you can feel them squirming and I had no confidence cornering. I hardly ride any mud so maybe that is a niche for it, but I hated this tire and removed it after low miles.