Couple of Quotes:
“Probably the only mechanic I’m not crazy about is XP and leveling. If I could, I’d build a system where gaining a new class feature is driven by story-based prereqs. Like, you can’t learn to cast fireball until you’ve defeated a fire elemental and captured its essence, or after slaying the orc king a fighter can master a new battle axe technique.”
“More dice, fewer static modifiers. I’d use a die in place of the proficiency bonus. I like rolling dice and find it easier to teach that way.”
XP itself sort of sucks for STORY games, I loved when Warhammer Fantasy Roleplay came around and the GM just assigned a logical number of points after a session or couple of sessions. And of course 13th Age where levelling up is completely via GM fiat — which is excellent.
Back to the old school though, I DO enjoy Lamentations/Moldvay style of XP where creature killing gives very minimal XP (fuck all that tracking) and the big haul of XP comes when silver and treasure are safe in some place outside the dungeon. Then you can take a natural break in the action and count out all the XP at the same time players are focused on counting out their silver coins.