Hm. Agreed on Tooth and Claw, Sun of Suns, Wintersmith, The Fall of the Kings, Ash, and Issola.

As for different books by the same authors I'm picking Iron Sunrise and The Last Hot Time.

Additions would be Doctorow's Little Brother, Bujold's Paladin of Souls which I expect you forgot, and Cherryh's Explorer because I did read them recently enough to remember which one was the best.

And maybe the Baroque Cycle, I haven't made up my mind about that yet.