My UO Experience goes by following:
Vetus-Mundus (German Freeshard) Some excellent content, but a little bit overpowered + i had some personal trouble with one Admin(no Accounts anymore)
-ABCUO (eng. pvp shard) Good shard for pvp, exception is no skillcap in sum but the staff is not bad (Accounts decayed)
-UODreams (italian shard) They looking like good peoples but i wasnt getting addicted like i thought (Account exist since 20 Days)
-Raistlins World (english Shard) Having Accounts there since 2006, staff is awesome and friendly, playerbase running between 20 and 100 in phases. Many Custom content and some cloned content from Lexia (ITS,Fishing). The Shard i actual Play
- UOLegends(spanish) UO-SA Clone people there are totaly egoism or dont understand any word in english. Staff is pretty hard to talk and rules are a little bit stupid (No Trade in luna, Participitation of Event without the right skills end in jail, Donation taking 1 week until you get and they are pretty expensive, Skilling needs too long[20 hours from 50 to 100 Magery])Account since December 2011 but dont play anymore
There are many more not longer existing shards i played. If i would need to vote i would say currently Raistlins World is one of the best shard in my list. The staff is friendly and experienced. Scripting afk is allowed in some ways(Bodding\skilling, Ressource Gathering in felucca) and one of the owner is an old moderator of easyuo(Tecmo if someone remind).
Content they have is a mix of SA\ML + Custom stuff like pvp champs,Custom Perless added and lot of more.