Tron Legacy. People just hate the "young adult male" demographic era of Disney for some bizarre reason, even though that was my golden era to me.

I think Hellboy 2 The Golden Army is much better than the first Hellboy film.

Since all the movies I wanted to mention have already been mentioned I go with a lesser known movie and franchise and say Police Story 2 and Police Story 3 Supercop.

Anything from the Purge series.

The first one was pretty middling, the second one was good, the third one was great, and the fouth was a bit below the third.

blade 2
spiderman 2
lotr the two towers!
aliens
the dark knight (legendary by ledger)
captain american: winter soldier
bourne supremacy


games:
witcher 3 coz its mainstream compared to 1/2 which i havent played haha
uncharted 2 or uc4 can't choose
gran turismo 3
can't really think of any other games coz they just all so good haha!

Watch Dogs 2 is better than Watch Dogs 1

And here I thought I posted this in the movies section. :P

Seriously though, it is funny how superior sequels seem much more common in games than in movies. Or maybe that's just me.

Witcher 2 is actually really good, I'd recommend it to anyone with a fondness for action RPGs.

Terminator 2 > Terminator 1

Empire > Star Wars A New Hope 

I actually like Batman Begins more than Dark Knight, so not that.

LOTR was all shot concurrently, so it really even a "sequel", it's one big movie. 

I forgot to add Annabelle Creation is the best of the three (though for the Conjuring, the first is definitely the best).

Aliens and Blade Runner 2049 do not deserve to be mentioned here.

Their predecessors are two of the best SciFi movies ever created.