While I'm sure it's not final at all, I really like that impressionistic Rings of Time cover!
I don't - it reminds me of the old copyright-dodging "Best Of Trek" covers...
I love the old BoT covers. This one would have been great if it were hand drawn in true BoT style, and not CG. As it is, it kinda reminds me of the faux-DS9 on the cover of the "Far Beyond the Stars" novelization.
The Vanguard and DTI covers are good.