"Biggest drop in quality" sequels

[Bienrico]

Super Mario 64 > Super Mario Sunshine
Wind Waker > Twilight Princess
Spiderman 2 > Spiderman 3
Halo > Halo 2
Mass Effect 2 > Mass Effect 3
Harry Potter 1 2 3 > Harry Potter 4 5 6 7
Resident Evil 4 > Resident Evil 5
Silent Hill 1 2 3 > all which came after including 4.