Spears are nice, I like the fact you could use a spear against a dragon and possibly get that extra ranged advantage but this might also break balance in the way combat is done and we might all favor spears over other weapons.
Horses are nice, I've seen some great horses done by games like Assassins Creed and Red Dead Redemption, but this might take alot more time to make than what they have...
My choice would be mounts considering I'll be running around with either dual handed weapons or a 2handed sword most of the time.