I dunno about the "one-on-one > group" thing - I RP on LiveJournal in a YuGiOh-themed community (Yes, the one in my sig xD *shameless plug*) and it's crazy amounts of fun. However, my RPing on Gaia sucked majorly and drove me to a 4 year hiatus that ended earlier this year.
So I guess what I'm trying to say is that RPing in groups depends on where it's done and how it's handled. Largely the ones on Gaia fail, while other sites (i.e. LJ) might have great ones. Really a matter of tastes.
Aaanyway, what're you looking to RP, exactly? I might be up for it =3
Edit - Holy what, necroed thread. o_o