What I would love to integrate into 5e are some of(not all, if only because the edition couldn't really handle all of it and play well) the movement abilities, whether it be more forced movement, or have flanking matter, but not advantage, maybe literally the +2 from combat advantage. Or even try out a type of mobility to boost AC or something, just to make those dex boys move around more. Maybe importing the rage powers from barbarian as an incentive to get those guys charging more. maybe making sneak attack not work as well if you just stayed still all round. I know this isn't a 5e thread, but I've just been stuck on the problems with lack of movement and while 4e wasn't perfect, it did way more than the editions on either side of it to fix that problem.
What are everyone's favorite movement based things from 4e? be it specific powers, or class features or whatever. For me, I saw sequestering strike(Avenger 3) and swift Panther rage(barbarian 1 daily) do a ton at my tables to get those characters moving all over the place. Runner up goes to Open the Gates of Battle(Monk 1 encounter), it got the monk to dash across the battlefield to hit someone that hadn't been hit yet by the party.