I have a ton of different products. Nothing even comes close to RealGuitar (MusicLab). Here's why:
• It handles both solo and strumming parts.
• You can put in simple three or four note chords and trust RealGuitar to turn that into realistic guitar chords—or you can define your own chords. A lot of programs are limited in the chord options. RG will do anything you could ever need.
• The up/down strokes sound more real than anyone else's, in my opinion, and the mutes and other articulations sound great.
• It comes with several steel string, a 12-string, and two nylon guitars. The stereo sample steel is particularly good.
• Since you can tell RG to play the chord in different positions, it is ideal for creating two guitar parts (left and right) playing different inversions (or neck positions).
If you buy this product, PM me and I can pass on some tips. The manual is not super clear on a couple of very important points, but once you've got it, it is a snap.
I actually played acoustic guitar on 1,000s of records but now I use RG on everything.
AAS is good for the price but less realistic. Vir2 Acoustic Legends HD is good for solos (though there is no stereo choice) and the strumming is limited. I do use it sometimes along with RG for variety. Vir2 has a new product out called Acou6tics that is supposed to strum well, but they claim it is based on the technology used in Electri6ity, which I find frustrating.
For electrics, MusicLab also makes RealStrat and RealLPC. I use them all the time. Excellent for solos or strumming.