Brightest 1Wers are probably those retrofitted with Elektrolumen's 30mm optics (R ranked). Wayne J's Blaster II was quite bright for a 1 Watter. Brightest 5Wers are "X" binned, if you can find any, and the closest would be Mr Bulk's Space Needle II (W ranked). Brightest 5W production may very well be the Helios or Mega6 from Inretech right now.
I'm sure others can also add on...