definitely the Timmy over the RC booster. both pedals are amazing, but the timmy is much more transparent and versatile. i've also had both twice, and the timmy has always outshined the RC even simply as a clean boost.
I have both and IMHO they are not comparable so no decision to be made. Th RC is an almost totally clean boost. You've really got to crank the gain to get any od at all with single coils. The Timmy is an OD but a lower gain one. It can be goosed into a bit higher gain but that's not it's sweet spot. However put the RC in front of the Timmy and you can extend the gain range of the Timmy a good deal. It's one of my favorite combo's.