We've had a change in the standings. RE5 has taken the lead over FFXIII, also, we have a few more that have had 2 or more votes.
Gears 2 6
Ninja Gaiden 2 3
FEAR 2 3
Tales of Symphonia 3
Soul Caliber 4 2
Prince of Persia has received 2 votes, but I don't think it is a sequel, is it?
As much of a sequal is FFXIII is to FFXII
Most Dissapointing... Oblivion Worst Sequal: Ninja Gaiden 2