dmbaer
HALion is much better at supplying conventional ensemble (real world) instruments.
I know nothing about the AIR option (but it frankly sounds way too good to be real).
Halion Sonic 3 looks good, but the $250 entry point, or $350 for the full version of Halion 6, is still steep for a tight budget. But it may be cheaper vs. Kontakt if you add up the cost of several Kontakt libraries to get the equivalent sounds.
The AIR stuff is actually very good, and the recent sale prices are hard to believe, but they are for real. AIR Music Tech is a German development group that has provided the instrument bundle that has been an exclusive Avid Pro Tools feature for years. Since inMusic has acquired AIR, they have been marketing these instruments in VST and AU formats. Some of their interfaces are dated, like some of the older Cakewalk plugins, but for the price, the sounds are hard to beat!