Pirates of the Caribbean Online (or Pirates Online) is my vote. No faction to choose (both PvP factions willingly take anyone; you can hop sides in the middle of a battle), it's cheap (9.99 sub, with a free-to-play option), and the PvP (at least ship-based) can be ****ing epic.
I once had my War Sloop, down to half hull, followed by two frigates. I thought of running, but instead spun around and went the other way. They turned to follow, just in time to see two frigates coming up behind them. They both panicked, I let off two broadsides between them, and slipped past just as the other frigates came along and finished them off.
****ing epic, man. Economy and politics? Well... it's a game designed for the younger set. It's really more for logging on in the afternoon, blowing up some ships or leveling, and then moving on to another game once your blood lust has kicked in. So, might be a good option for a "casual" MMO.
Other than that, I'm up for WoW, STO, or LOTRO. I've got two maxed characters in STO, I *think* a 37th level hunter in WoW that I can dust off, and LOTRO is always fun (I just don't have any characters in it).
Star Trek Online is my second favorite pick though. PvP is in need of some fresh blood (all the PvPers on their forums probably qualify for bitter vet status), and they just released the Foundry which allows for player created missions. Plenty of RP potential, and if mixed with some PvP I'd definitely sign up. I also have a lifetime subscription (thank you family!), so I'm in it for the long haul.
To be blunt, with politics as it stands currently in STO, I
desperately want to start up a fleet to get some political stuff brewing. They do have a "ambassador" mechanic that gives you special perks for completing non-combat missions. Economics... kind of a non-issue, but the simplified crafting system is something that vets of EVE Online shouldn't have any problem mastering in a week, and exploiting in a month.
PvP; seriously, no consequences unless you change the difficulty setting and start taking damage to specific systems. It's fun to just sit back, do your thing, and if you're into tears... there's nothing sweeter than seeing people say, "Dude, you think this is hard, try EVE," to someone complaining about being blown up in PvP. People really do say that too, I'm not exaggerating.
WoW is my least favorite option, as I'm two expansion packs out of date and I really don't want to spend 50-60 bucks plus monthly sub to get back into it.
I'm neutral to LOTRO, it's fun, but... well, meh.
Champions Online... meh, might be interested if my computer didn't hate it with a passion. It's made by the same people as STO, with the same game engine... yet my computer can't run it.
So... number one pick would be Pirates Online, second Star Trek Online, WoW only if people won't laugh that I don't have all the expansions, and even then I might decline.
For reference (and if anyone plays those games who want to have someone to team with)
PO:
Amann Karris, "The Darkest Heart" guild, lvl 37 (usually on Abassa Ocean server).
STO:
Mal Caine, Human, Science, no guild, Lvl 51 and
Koth, Federation Klingon, Tactical, no guild, Lvl 51 (both Federation characters)