The reprap wiki is always the place to start
http://reprap.org/wiki/Category:Hot_End
Generally those hotends using PTFE as a structural material are considered prone to failure. Most use Peek with a PTFE liner, but there are a number of newer hotend designs that use very thin stainless steel barrels and forgo both.
In terms of pre made hotends, JHeads have a good rep, as do Buddaschnozzle's and the arcol hotends.