Only really got into three different metagames during my time of competitive pokemon. I found the community and people you played it with made it the most entertaining though.
GEN V LC
Very balanced metagame, with no changes or shifts in a long time. Plus you get to use cutemons =3. Very small community in comparison to the other metas, had alot of fun. Most of the regulars knew each other and could help play test and smooth out kinks etc. Also was the meta i participated most in forum wise. Only downside was that it grew a little stale, with no shifts and only a handful of powerful staples meant that there was not alot of diversity in teams, with three mons above 30% usage (for good reason though, they are great in the meta).
Others
GEN 4 OU
Ah the good days of exploding lead metagross. Found this to be very fun, a very different playstyle to Gen V.
Gen V NU
Great fun, get to use mons that you would most likely never try in the higher tiers, did not get stale with alot of different viable playstyles.