637nm Vs 640nm Opinions

Hi all,
Looking for some opinions on which red to choose from.. for a RGB - Mainly doing beam shows but will do animation also with FSB3.
I've had countless nights reading though this forum and just can't decide.. Loosing sleep over this :) going to work mumbling to myself 637nm 640nm..
I'm looking at Red 350mw - 500mw - Green 500mw, Blue 1W

Thanks guys :)

Much the same, if your referring to kvant reds. Everybody has pretty much stopped using 642 for 637 due to increased power and the diodes are easier to work with being isolated cans. :-)

the choice is simple really

if you already have 642, stick with it
if you don't, go for 637