I love the Third Party Viewer Directory page because it indicates those viewer with out of date features and then lists them all by crash rate and stability. (some viewers I use are not listed if they aren't officially approved)http://wiki.secondlife.com/wiki/Third_P ... _Directory
Each viewer has it's own pros and cons, just like everyone has different preference, and computers can be so different your performance might vary.
The last few months I was using Catznip for about 90% of my SL and giggling about finally having a stable well performing viewer, but I'm giving Dolphin a pretty hard test tonight and it's surprisingly good. On extreme settings at a club and not a blip. It also has a few features I forgot how much I missed from other viewers.
Still will switch to Niran's for photography though.
ETA - You can always try the official too.