Would you power up or completely max a 98% mon?

Depends on the Mon, but if they're actually useful in the current Meta as Raid Boss attackers, then yep, I'd power them up.

%98 is about as good as you're likely going to get for most useful Mon's. If you do get a %100 in the future, hey - you've got two awesome Pokémon.

My play style is this:
Only 1 of each type unless it has a shiny or gender variant. I keep the highest IV% of each. Yeah, I waste dust into them only to replace them later, but since there are heaps of pokestops and pokemon around me, I can replenish my dust resources pretty fast. Also, I only power up/evolve mons that are in the 80%+ IV range, unless they're shiny.

Yes I would max a mon with those IVs

Yes I have powered up this Machamp to max

I maxed a 98%

Tyranitar
Entei
Raikou
Zapdos
Exeggutor

and plenty of Mons with even lower IV. I hate waiting for that 100% that probably never comes.

Just ask yourself: Do I need them to be maxed out?

I haven't got any at lvl 40 (will max out my Mewtwo soon though) and it's not like I'm having trouble taking down gyms or doing raids (I don't solo lvl 3 raids).

I've got an 98% Dragonite at lvl 37 and even though I'm sometimes tempted at taking it all the way, I know I don't really need to. I could probably have even kept it at lvl 35.

Yes I would power up 98% if it's a mon I want to power up in the first place.

I see it as a Win-Win situation. Either you never ever get a 100% mon and you win because you powered up the 98% and didn't miss any opportunities to use it, or you do eventually find a 100% version and hey, 100% is so cool to find or hatch in the wild you will be happy even if you wasted stardust on another. To me that's still a win.

I've only brought a couple to max so far. It's SO. MUCH. DUST. unless some specific break point is reached. In other words: not worth it for a few meaningless digits and no commensurately gargantuan increase in performance.

I maxed my 98 Scizor, got a 98 Vaporeon from raid and I’m not maxing it cuz I have 3 other Vaporeon that reached 3000+ CP IVs 82-91(I blame the old gym system haha) also got a 98 Flareon but don’t think I need to invest because I have a perfect charizard a 93 Moltres and a pretty good arcanine almost maxed

Caught a 98% level 1 Dratini back in August 2016. Evolved about a year ago and got Steel Wing/Dragon Claw, so I never did anything with it. When I started getting extra fast TMs, I changed it to Dragon Tail/Dragon Claw. After stockpiling stardust with this recent event I finally pulled the trigger and powered it up to level 35. I'll take it higher when I get some more candy.

Of the three pokemon you listed, Machamp is the most useful, even in multiples. There are so many common defenders that are weak to fighting. I am frequently using at least my best two level 38 Machamps when fighting gyms. I also have three more in the 30-33 range. I can only assume that most people don't have experience using Machamp because I occasionally will see seemingly diverse typed gyms that are actually all weak to fighting (normal, rock/ground, ice/water, normal, steel/ground, rock/dark). Assuming Machop candy is as plentiful in your area as in mine, I would at least evolve the Machop to see what moves it gets.

There are only three Pokémon whom I refuse to have or power up if they are not 100%. They are Mewtwo, Espeon, and Tyranitar.

-Mewtwo is my favorite Pokémon, and a 100% Mewtwo is my ultimate goal in this game, so any Mewtwo that I manage to get from an EX Raid (if I ever get a pass) that is less than perfect will not be powered up, but will be held onto to only for candy accumulation. Tough goal, for sure, but that's what continues to motivate me to play the game.

-A 100% Espeon so I can have one at exactly 3000 CP when I power it up to lvl 40. I still don't even have Espeon registered to my Pokédex. If I really wanted to, I can evolve one of the Eevee I'm holding onto right now to Espeon, but I only keep one of each Pokémon, and I refuse to have and invest in an Espeon less than 100%. Until I find or hatch that perfect Eevee, there ain't ever going to be an Espeon in my team.

-And, I want a 100% Tyranitar because I'm not satisfied with the one I currently have, and the 3670 CP looks very nice on Tyranitar. I barely use the one I have, and I don't like that I barely use my Ttar. I did max mines out to lvl 40, but only to try to get the most out of its attack IV, which is at a low 11 ATK. :/

Other than these three, it doesn't matter if the Pokémon isn't perfect. As long as they're above 90%, only then will they have my attention. That's how I'm rolling, so far. :]

I only level up Pokemon regularly if they are 87% or higher and raid relevant. After that, I save leveling for when I can reach critical points, but I normally stop at level 30 due to issues of diminishing returns.

I have maxed to Lv 40 only 3 mons: a 96% B/C Ttar, a 98% DT/O Dragonite, and a 100% WG/AT Vaporeon.

Since then, I have acquire a 98% B/C Ttar, a 100% DT/O Dragonite and a 100% WG/HP Vaporeon which I have powered all to Lv 31 for now, I’m fine with that.

My only 100% mons are a Magmar and a Growlithe.

Yes

I have 3 maxed Pokémon:

3157 100IV vapor
2268 100IV Victreebel
2909 98IV eggy (ZH/Seed)

That said, I had invested a lot of dust in the 98 eggy in 10 stack days for gym diversity and the extra investment recently was simply just because...the last 2 were for the sole intent of getting an eggy above 2900 though.

I max out my best mons. I don’t agree with the approach that many have to only power up to L30. A raid squad of L30 mons is a mediocre team. I like to max my chances of getting more bonus balls, and I won’t get there with a mediocre squad.

To me, 100% or 98% are more or less the same when considering power up or max out or not. Plain simple!

Yes for the most part. Also got 2 98 Machamp, 98 Golem and 100 IV Espeon and jolteon.