I don't think there's really a "Best" at the moment. It's definitely all a matter of preference, and apparently which version you have. 7 has the most mods, but more doesn't mean better. 8's modding team is super dedicated and the stuff they are pumping out is amazing. 7's modders are also pumping out some really cool things, with more on the horizon. Hell, even 9's modding scene is still going pretty well. Moguri is getting updated, a new rebalance mod was recently released as well.
