Approaching this mainly from a DM/Designer perspective.
Favorite: Human. Mostly because I like an understandable world, and having the majority of the PCs be human lets the non-human characters stand out. Basically, unless you have a specific urge to play another race, human should be the best/default option.
Disliked: Dragon Ogre (this used to be a race in WHFB). Not really because of what they were, but because of what they represent; pile on more and more and you end up over the top and trite. The Dhampyr is in the same class for me, but I guess it would be possible to build a cool campaign around Dhampyrs and Shardminds - if that was what the campaign was all about.
Gnome Domination: If I ever found a gnome in any game, I would ask.