The more I hear about the 3 action mechanic the more I like it. That and the shield mechanic had peaked my interest now.
Bard, Druid, Ranger.
Before my first game of 5e, my group was playing Rise of the Runelords with PF1. I was playing a storm-themed druid. It was a bit OP, especially casting spells as a lightning elemental. I would welcome a nerf. But I am glad to see that the storm druid is one of the themes available for the PF2 druid. So one of my first character creation exercises in PF2 will probably be recreating the character.
I got my books last week, so this feels a little like cheating. What I like is that they appear to have taken 3e/Pathfinder and rebuilt it on top of consistent framework. I like that all checks resolve the same way (no different crit/auto success/failure for attacks, saves, and skills). That should make the game easier to teach, though I fear the written rules may be a bit intimidating to new players.
As a GM, I’m looking forward to running monsters with interesting abilities. For my players, I’m looking forward to their having more options for their characters. The three action economy should be fun. We used the Unchained action economy in PF1, and I thought it had evolved nicely when I played in a demo at Origins last year.
I particularly particularly like how multi-classing integrates with the feat system. And the different levels of success or failure. I look forward to seeing if multi-classing has been refined in the final product.
Coming from 5e DM and occasional player I am looking forward to monster's being more dynamic (was hoping for more of a 13th age vibe but at the same time the bestiary is filled with great monsters), access of Paizo adventure paths, 3 action economy, PC's that feel a bit more epic, and more character options in general.
Three action mechanic.
Death mechanic. I prefer death to be a little more dangerous. I'm glad pop up healing is gone.
Initiative. I like not having to make a Perception check, then roll initiative. Removes one encounter step in a fashion that fits pseudo-realism.
I'm glad PF monsters kept spell-like abilities and longer duration abilities that can be used out of combat. One major thing I did not like about 5E is every monster block being heavily focused on combat with no non-combat abilities I can recall.
Shrinking the gap between fighting styles was very nice too. I like every type of fighting style being viable.
I'm looking forward to potentially playing in a game while the edition is still new, and nobody has any system mastery. The freedom to experiment, and get things wrong, is a refreshing change of pace from a game that's already been solved.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.