bug fixer fixes annoying bugs in Rome Standard,
RTR changes the game entirely

both have their merits

if you want the fun of fighting the civil war, the challenge of keeping the Senate happy while competing with the other Roman Factions then go for Bug-Fixer

once you have tired of that and want a straight out, "no-pope" game, then go get RTR (or SPQR or EB or one of the many very good mods out there)

(i have not tired of the standard game yet, but i already know i will be soon enough, so i am keeping an eye on several mods i may want to play)

cheers,
B.