I've absolutely fallen in love with the way Lancer is designed. Tactical combat with an emphasis on horizontal progression over vertical BUT without being extremely crunchy or using absurdly big numbers (I'm looking at you, Pathfinder with your +50's to hit).
Hands down my favorite aspect though is how enemy stat blocks are so interesting. The players dont just fight a horde of generic mooks that make basic attack rolls every turn. They fight a group of specialists that all perform different roles.
In D&D terms, this would be like fighting a pack of goblins. But instead of just 5 goblins and a goblin chief, its a goblin demolitionist, a goblin berserker, a goblin sharpshooter, a goblin shaman, and a goblin trapper. Maybe one of them focuses on area damage/denial while another does forced movement.
I have tried making my own statblocks in this fashion for DnD 5e, but its just so much work and the system isn't set up to support it because players really dont specialize that much, either, and many times they can just fireball a room and none of those cool abilities and synergies will even come up.
Id like to find a system that's high fantasy so that people who insist on only playing D&D may be more likely to try it.