Every cyclist ends up having a set of tires that they trust above all others. For myself it is the Continental GP 4000S. Not exactly the cheapest option on the market, but a great combination of performance and durability. Since I have only one set of wheels I choose to use a single tire for both racing and training (which obviously ignores one of the benefits of clincher tires in that I could easily have both). However here in South Florida where I ride the roads tend to not be harsh enough to force the need to use Gatorskins; so the GP4000s fit the bill nicely.
Recently Slowtwitch did a great write up on the entire GP4000 line from Continental (here). I had been considering trying out the Attack\Force line and this article did a good job of breaking down if I really should consider making the switch. In the end I am planning on sticking with the GP4000 for now, but I am now considering trying the 700 x 25 mm version of the GP4000 line on my rear tire to see if I see any impact.