Is a level 29 98% WP Vape worth maxing out?

Should've walked it for a gen2 evolution. If you don't need a defender right now leave it as is.

Wussup, dawg! How 'bout a 2 charge move prestiger then?

If you need additional defenders with high CP for good placement, then Vaporeon is a good option since the candy is readily available. Otherwise, meh.

I'd power it up, no question. I have 6 Vaporeons (various movesets, IVs from 75-95%) that are all sitting high in gyms at the moment. A 98% IV is practically guaranteed to get you a really nice spot in a gym, and it's already a high enough level that you don't need to invest too many resources.

Sure it's worth lol.

Doesnt matter the move set all vaporeons with high iv's like yours are worth powering up all the way. If you are low on stardust is another story but just after Blissey, Dragonite and Snorlax i find Vaporeon the 4rt best option as defender. Sure Rhydon, Gyarados and Tyranytar will have better CP overall but are weaker defenders due to their double weakness. Also evee candies are so easy to find around compared to other so you can always have an army of Vaporeons with very nice CP's.

For me every Vaporeon is welcome in my team doesn't matter how many if their IV is over 90% or similar. They are extermely good defenders and depending on where you play, Vaporeon will normally sit close to the top on the gyms.

Definetly power him up.

Do you have a ton of stardust? If so, than yes, I'd max it out. If not, keep it the way it is. At level 29 it's probably around 2500cp, so pretty useful as is.

I think it's advisable to start hoarding stardust for the eventual gym rebalance. It would be more advantageous as GGTW said to use Vapes for prestiging, but it looks like your little friend is lvl 28 and probably too high for all that jazz.

I'd definitely hang on to it and see what happens with the gym overhaul. At the very least you've got a serviceable attacker you can use at a good CP.