Alcanafin- Haha, that shark is a major highlight of the first. 
And you’re right, the dialogue and jokes in the original work so well on an adult audience that, although the same does apply to the sequels, I don’t think those mature jokes ever reached the same sort of height and quality as the first.
I’ll go with 3 because it had very good jokes. 2 had loads of them but 3 had jokes that were hilarious. 1 is a close 2nd but 3 wins for me due to an excellent ending, good story, & hilarious jokes.
I said my favorite was the first Toy Story. It’s simply because that’s the one that I saw first and it’s one of my first memories as a kid watching Toy Story, and no other movie can ever have that spot in my heart, even it it’s a sequal to the same movie.
^^Nice avatar, I love Green Day.
Now, I think Toy Story 3 has grown on me, and I can give an honest answer. Well sorta, by now, it’s just a tie between Toy Story 3 and Toy Story. Toy Story 2 and Toy Story are great in their own right, but Toy Story wins in nostalgia.
Since Toy Story and Toy Story 3 are so different that it’s pretty much impossible for me.