I love to powerlevel too and destroy bosses.
Lost Odyssey
I hate games that reduce the EXP you get the higher your level is.
Trails of Cold Steel Series
Same as above. The higher your level the less EXP enemy give. I HATE THAT!
Suikoden Series
EXP Scaling
Rogue Galaxy
Exp Scaling
Legend of Dragoon
Enemies give so little EXP that it takes forever to level up one level. Mostly you just level up from bosses unless you fight very rare Unique Monsters.
TESO
Stopped playing this game after they put level scaling in the game. You actually get weaker the higher you level until you reach max.
Bizarrely enough I never had any issues with Suikoden's EXP Scaling system.
Essentially if you are over-leveled you get peanuts, and if you are underleveled you might get multiple XP bars at once. It doesn't differ much from traditional leveling and instead of showing an ever multiplying XP bar, it just shows essentially the percentage bar of that. There might be some diminishing returns if you are over-leveled so you won't be, but it's extremely important if you are leveling a bench-sitter character to make him quickly relevant in a couple of battles. Works perfectly for a game with 108 characters and just 5 slots in your team.
Also, as I just mentioned, I give a free pass on MMOs using scaling. Those worlds are intended to be lived in and not just passed by like solo RPGs, so finding ways to keep them relevant is essential. I've played plenty of WoW in my life where they advertise all those beautiful new areas in each expansion, and once you reach the end level you'll spend the rest of your life on the few miserable zones the game intends for max levels.
I don't give a free pass however to badly distributed exp systems like Legend of Dragoon. Getting the bulk of your levels from bosses is very annoying, especially since you might end the fight with a downed character or 2.
Still, even if badly implemented, it's still traditional leveling without scaling, and there are obvious advantages to becoming stronger, therefore it's off-topic here.