I have Visi-Therm Deluxe Heater's on all my tanks I they do a very good job on all my tanks , bought mine from Doctor foster & smith , dont know if they are the best out there but they do a very good job and for the price you cant beat it , heres a link to where I got mine http://www.drsfostersmith.com/Product/Prod_Display.cfm?pcatid=3852&inm=1&N=2004+112984+113565 your best choice would be the 300 W one , hope this helps !
I researched this question a few months ago, and the result I came up with was either an Ebo-Jager or Visi-Therm.
I got an Jager for my new 38g and shortly afterwards a VT as a replacement for my 10g (would have gotten a Jager as well, but couldn't find a 50W at the time). Both are very accurate. The Jager looks a little more durable but I think you can't go wrong with any of them.
Both heaters are sold for similar prices online, but are very expensive in stores so check before you buy! Mine came from Big Al's.