I don't play GMOD anymore, I mean it's still there installed on a drive somewhere, but I don't honestly feel the connection. I'll watch PH videos on youtube and they're fun to watch.
My favorite gamemode is DarkRP, although I will say a very detailed and worked on gamemode is TTT, simply because it is so customizable and is one of the bases for gmod.
In TTT great mechanics, but if you want good RP - you need SWRP. Unfortunately in russian sector all best SWRP server were closed( I try made good RP server from scratch, but subject HL2RP with mechanics from SWRP, TTT and DarkRP