Ragnustus, I strongly recommend that you also look into what timezone you are currently in and join a shard that closely matches that timeline. Events will often happen at almost any time, and if you're on the west coast where an event is happening at 9am, that means it's 6am for you. Alternate wise, if you're on the East Coast and the event is at 7 or 8pm, that's 10 or 11 for you.
On other games, like the ones you mentioned above, the events happen when your guild decides to run a raid, so it's flexible. But here on UO our events are well planned out by our EMs, so you may want to take that into consideration when picking your shard.
That said, if you're a West Coaster, like myself, I strongly suggest Napa Valley. Great community and lots of room for houses (I placed a keep on accident when I first got here).
UO is very much alive, even if it's not expected for us to get many more major content updates in the future. We've got lots of flaws here, but compared to some other games... we're pretty clean. Also, we're 16 years strong! Hoo-rah!