RP and general social activity is still good. There are also numerous RP events happening throughout the month that you can be a part of, if that sort of thing is of interest 
Like someone else said, Alliance is larger and you will find more walk-ups there. However, since you are also looking for a RP/social guild, Horde will suit that just as well. Guild RP is in general great on the red side and they also have a fairly large discord where you can find resources for events, guilds and general RP =)
Good luck and welcome back if you do decide to re-sub! 
Had to look a bit but here is the Coalition of the Horde info if you want to take a look!