Both formats offer great sound. I'd recommend SACD, if you are primarily a 2 channel listener. The reason is that all SACDs have a discrete 2 channel layer. Some DVDAs do not, and that means that the 2 channel output is created in the DVDA player via a mixdown of the 5 channel information on the disc. This is ok if you've got a really really good DVDA player.
In general, I'll take the option that involves less work on the part of the hardware. Shortest path, etc...
The other reasons to prefer one format over the other are purely personal. For instance, I find some DVDA's hard to play without using the TV screen menus, and I don't have a TV in my listening room. May or may not be an issue for you.
Another reason I prefer SACD is because the format will have longer legs than DVDA. Both are niche formats, but DVDA seems to have morphed into DualDisc, which may or may not have a hi-rez (true DVD-A) layer.
Cheers.