So what what’s more important when deciding what Pokemon to level?

Moveset is way more important.

Although be careful, for some pokemon the best and second/third best movesets are very similar. For these, use IV then. For most pokemon, the optimal moveset is a way bigger improvement than any IVs ever will be.

Probably moveset because IVs add only a relatively small benefit to stats & overall CP, but this is a situation-dependent question. How good/bad are the IVs vs. how good/bad is the moveset? Also, how rare is the pokemon in question?

If you've got the best moveset for a relatively hard to obtain pokemon- that trumps IVs, but if its something more common like a Vaporeon, focus on getting IVs first and settle when you have the best moveset with the best IVs and get the best of both worlds.

I think I'll stab my eye with a fork every time this question keeps popping up! Ok just kidding. Haha.

Move set > IV but strive to have both high IV and best move set.

If you are a serious player you need to get to level 30 asap. Best thing at level 30+ is wild mons can be up too level 30. These you can evolve and use without any stardust invested. Level 30 evolved mons include 2600 Rhydons, 2300 cp vapes/jolteons and 2600 CP gyrados. Great to use while you put together your high IV all star team. Above level 30 the only advantages are you get to power up mons to your level +1.5 and catch mons at a higher success rate.
I also highly recommend not powering up mons till you hit level 28-30. The faster you level the longer you should wait. While you learn the game its good not to get too invested in mons that you may later on regret powering up. 1 good egg hatches can cost around 80K stardust and 60 candies to get to level 30.
Oh and read Q&A here like its the daily newspaper and you will soon be answering questions yourself ;)