Vplayer and Rockplayer
On my HTC incredible I like vplayer the best for codec, speed, and streaming support. Rockplayer is my second choice only because it appears to be a bit slower. Slower being more likely for video and audio to get out of sync. Great streaming and coded support though. I use both with Upnp/dlna browsers skifta and upnplay alot. However vplayer currently is not working on my xoom. Rockplayer has been the most reliable full codec player on the xoom so far. Though I'm hoping vplayer gets updated soon.
Yxplayer has a nice feature set including built in windows share/samba and upnp/dlna support, but was very buggy and crashes on both my incredible and xoom.