Jump

Except that it says once per turn in the spell

lol...Dunning Kruger says hi.  The spell says nothing about the landing counting as part of the jump, or about superceding the fall damage rules.  You're literally just making stuff up.  The only thing the spell says is that it allows you to jump 30 ft.  The spell allows you to magically propel yourself with more force than your legs could naturally produce. If you choose to jump 30 ft straight up, then you're 30 ft in the air.  Gravity takes over at that point and normal fall damage applies.

Yeah, the key thing to remember is you're jumping "to" a location.  What happens after reaching the location is not included in the spell.  Just because you can jump onto a bed of caltrops doesn't mean the caltrops won't hurt.

D&D doesn't support competitive high-jumping mechanically.

It's a bit dissimilar that just that.

1. You have to spend 10' of movement to jump 30' in any direction with Jump. With Misty Step, you just teleport 30' without having to spend 10' first. Advantage Misty Step by 10'. This is small potatoes.

2. Jump is a level 1 spell that lasts a minute. Misty Step is a 2nd level spell that is instantaneous. Big potato advantage for Jump.

3. Jump is movement; Misty Step is a teleport. Even if you use Jump to go up or down, this is a massive combat and utility advantage for Misty Step. No opportunity attacks, avoid all barriers and hazards, instant get of grapples/Restricted/0 speed conditions/and yes, even a frickin' "get out of jail" for free card. This is a giant potato.

They seem pretty balanced to me, with Jump having the clear advantage for mobility and resource value and Misty Step having the clear advantage for pretty much everything else. Put simply, many things can stop Jump, but very few can stop Misty Step.