I would play a Star Trek MU, especially if in the newly envisioned universe. I would also play a GotG themed Marvel game.
As to the idea of a pay to play MU?
Fuck that. Fuck that so much.
It seems half of the time I play a game, there are elements of staff and other players who cannot be expected to be ethical for free. The one saving grace that makes me eyeroll INSTEAD of getting angry at them for being unethical cunts is that it's free. It's not as if I was paying for a service and they took my money, pulled unethical OOC bullshit, and ran. I would say easily a third of the people who run MUs shouldn't be trusted with simple, free, fair ethics, let alone anything resembling monetary transactions.
Point in case: Zero from New Jedi Order was taking PayPal "donations" to boost people's characters, run scenes for them, etc. Like a pay to play mmorpg environment. The end result is people complained about paying for things and never receiving them, and his lack of grace turned to a lot of badmouthing his critics.
So. Yeah. Let's never change the landscape of this corner of the hobby from "for us by us" to "money making venture".