It all depends on what you're going after and whether or not you've got a boat of some kind.
I grew up fishing one of Somerville or Gibbons Creek at least once a week from the time I could drive until I graduated and moved away from B/CS.
I've never caught a black bass at Somerville but have caught a ton of whites & hybrids and didn't have a boat. From what I hear, it's still pretty much the same. Very good lake for whites, hybrids, and crappie but pretty spotty for black bass.
Gibbons Creek used to be one of the premier lakes in Texas but it drew so much pressure that the fishing sort of tapered off and I'm not sure why. There's a larger story but I forget the whole thing. Anyway, even when shorebound I always caught tons of black bass there. I caught my personal best of about 9.5 pounds there. Two spots to hit are all along the earthen dam up to the spillway (all the rip-rap provides a lot of structure) or the dead, flooded trees across the cove from the boat ramp. We used to wade in those dead trees and do pretty well.
As for Conroe, I've also never caught anything but crappie, whites, and hybrids there. For years it was a pretty dead lake because of the hydrilla and then the explosion of grass carp that ate all the vegetation but over the last 10 years or so it's garnered a better reputation. However, I do second the idea that the fishing is much better above the 1097 bridge unless you're trolling near the dam for stripers.
I've never fished Fairfield but I have fished Fayette and even though we caught tons of fish they were all very small, in the 2-3# range.
Former Hall of Fame level poster w/ Ag tag who was banned for bagging on fran. Now that the wicked witch is dead I have returned.