I'm one of those who feel that Thor is an underrated film, and consider it Thor's best, slightly better than Ragnarok.
I know most people disagree, but Kenneth Branagh crafted a simple 90 minute family drama about Thor learning humility and regaining his status. It is, perhaps, a little stiff. Thor 2 was a mess story-wise, and Taika Waititi's Thor was too stupid and silly, often undercutting the dramatic moments with more slapstick humor.
X2 is a great film as well, but its story was a little bit of a mess. Lots of moving pieces, lots of characters to juggle, and only a few got any meaningful screen time.