Hmmm, two votes for Ride-By-Attack and one for Spring Attack. Consider me boggled. But then, I like Dodge and Mobility too. Anything that helps control the field of battle. But RBA? Mounted charges are pretty silly without it...
My vote is again for:
WEAPON SPECIALISATION
As Crothian put it a few threads ago, you have to wait for four levels of Fighter, and then still burn a feat for this?
[I'm partial to Ranger/elfy goodness.]