Best sail I have and have ever sailed is my 8m Speed Demon from Hot sails Maui.
Don't think I have had a bad sail experience.....there have been sails that have not worked for me but I am sure they would have been fine for another sailor.
Best wave sail - Hot Sails Maui Super Freak Maui Edition 5.3.
Worst wave sail - 2008 Ezzy Wave SE 5.2 - felt stiff like it had camber inducers.
2nd worst wave sail - 2007 Maui Sails Global 6.2 with an Ezzy mast
2nd best wave sail - 2007 Maui Sails Global 6.2 with a Maui Sails mast
Best slalom sail - Maui Sails TR5 7.6 - light in the hands, powerful and faaaaaaast.
Worst slalom sail - 2007 Ezzy Infinity 7.5 - heavy and slow. On the plus side it should last 100 years.
Best sail : NP warp Speed 6.3 It would get me planning before anyone else in 10kts,but smash me in 14kts. Very narrow wind range.
Worst sail Wild Winds speed trial 3.2 with about 50 cams in it. Never got it to work, tried soft and stiff masts. Just too short in the boom and twitchy. Loved most of the other WW but not this one.
Faves are NP RAF wave 5.5 from 86 I think.
Gaastra Grind 6.2 wave in 2000 from when Barry Spanier went to Gaastra.
NP Evo III 7.8, just plain awesome.
Worst, TR1 bastard of a sail to rig with crap monofilm.
went OK when finally rigged though.
best sail---5.6m 2009 severne code red---has a lovely small feel to it,unlike the 6.2m Reflex which feels quite big.
best board--2011 i-sonic 90 litre wood carbon
worst board--2008 i-sonic 76 litre,front foot always wanted to come out of strap.