Dragon Age II.
...wait, no, I prefered it to Origins.
My vote would go to---
Oblivion - even if it doesn't quite count as a sequel to Morrowind. It was a follow up in the same series, and I think it sucked the soul out of TES and turned it from art, into nothing but a simple game. Yes, I have a possibly pretentious angle on this, but whatevs... Oblivion set the stage for Fallout 3 and Skyrim, two similarly simplistic games lacking in any real creative identity or depth.
(disclaimer: I still put a ton of hours across those games, and still greatly enjoy Skyrim. but for me, Bethesda spiritually died a little death with Oblivion, in that nothing like Morrowind will perhaps ever be seen again. at least not from them)
Tomb Raider 3 - the point I bailed from the original series. An ugly, messy, disjointed Lara-goes-on-holiday mishap, that arguably began Lara's and TR's decline in cultural and gaming relevance.
The Force Unleashed 2 - the original remains one of my highlights from this/last gen, but the sequel I avoided like the plague based on the horrible demo and poor reviews and fan feedback. I watched the story cinematics on You Tube, and it seems to have messed up everything the original did so well with its treatment of Star Wars.
Halo Reach - there is a lot to admire about it (my favourite Halo MP, customisable campaign Spartan with gender select, a squad of Spartans was a great idea, etc), but I think it's a largely irrelevant entry that added absolutely nothing to the series, the lore, or the gameplay (barring the great tweaks to MP). Superb presentation, a few nice levels, and classily made, but for Bungie's last Halo I thought they went out with a puny whimper (Halsey's journal from the limited edition was awesome, however, and ended up being far more interesting than anything in the game itself).