Elixer Choices

What should my next elixer upgrade be?

Army camps.

Since I dont want to turn my head sideways.

upon getting th8, I am assuming you'r army camps and spell factory are already maxed, so you need to do the lab immediately and constantly have troops upgrading in it. farming troops first then the rest. obviously in order of usefulness to you right now but also realize other strategies are going to become more usefull later on so max ALL you'r troops.

As for the other upgrades, max both you'r new storages as a fairly high priority. other then that their really isnt alot of elixer upgrades at th8. The de storage takes lightning attacks better when it is upgraded. you may have gold mines still to do but their isnt anything else that is absolutely crucial. just get them all done before th9.

edit - oh. if you'r camps really arnt maxed you need to do those ASAP until they are all maxed. you should have maxed them out at th7. they are like the most important upgrade in the game along with the lab. if you had done them at th7 then you'd have a nice th8 transition wich wouldnt have cost hardly any elixer.

To answer the OP... everything... that's a fair job not taking advantage of town hall 7 loot, so I would not go to town hall 9 for about 4 months.