They are not on sale anymore (sale ended the 28'th) but the money you put out, they put into the sim ;)
Fokker D.VIIF <-voted best plane on their forums
Fokker Dr.I <-if you want to be the red baron
SPAD 13.C1 <-pretty decent bird
S.E.5a <-not so bad either
avoid the Nieuport 17.C1 at any cost! It flies like my granny cycles in tour de france! I made a skin for it, before I tried it in battle...and added curses on the rudder, after trying it in a dogfight :)
The planes you get in the RoF:ICE edition is enough to have fun with for quite a while.
If you're put off by their plane prices, just wait a while, and get fieldmods for the ones you like.
EDIT-> Its one helluva fun sim.. no hitech at all, just what you need after playing DCS games for a few days.. just the joy of flying!