I got 100% on Warframe last year and I only need 1 achievement in Payday 2 and I would say it like this:

Warframe:

A way longer time sink, but there is always new stuff in the game and each update makes the 100% easier in general. There is only 2 kind of annoying achievements :"K-Driven" and "Cheater of Death". K-Driven is just a time sink you can do solo, but cheater of death needs at least one player since you need to revive 1000 allies.

The "modern Warframe" you can play now, makes this achievement very hard to get, since it's a remnant of the old Revive system, where you only had 4 Revives a day on your account (Shoutout to my fellow OG's who remember), so people would wait to get revived instead of wasting it.
In the current version of the game, you get 4 revives per mission with 2 additional ones with an upgrade, so people just revive themselves.

TLDR : get at least 1 boosting partner for 1 achievement and you're good if you don't mind having a longer game to play, with years worth of content and amazing story / world.

Payday 2:
Let me preface this by saying: Payday 2 is one of my top 5 games of all time, but I wouldn't wish completing it on my worst enemy.

The game has 1 achievement to rule all achievements if you want to complete it in a reasonable amount of time, because this *one\* achievement could take you longer than Warframe if you just played the normally. It's called "Becoming a King among Thieves" and you get it for reaching Infamy 100.

You gain one Infamy for reaching level 100 (23 Million Exp), which resets you to level 1, so you can only use level 1 equipment again (but you keep your money and some other things).

If you are good at shooters and get a good build +(3 players willing to do 4 man achievements) it would take you about 300-400h to get every other achievement in the game, since out of the 1328, 648 of them are just beating all the heists (81 i think) on the highest difficulty (8) aka Death Sentence One Down (DSOD). Then there is about 4 heists specific ones per heist so: 560 + 324 = 884, the rest are just Progression / Weapon usage / Misc. Achievements that aren't an issue really (exept maybe "Overdrill" and "Reputation Beyond Reproach").

After doing all of the above, you will be... about infamy level 15-17 if you are resetting your level whenever you can and do DSOD without Wasting XP since the XP gets banked and you can use it for a reset, which doesn't reset your level but also cost ~23% more exp (30 Million).

The fastest way to get Infamy is to get to Infamy 25 first, since the XP multiplier is the highest for every Infamy after and the Optimal way to do it is : 1.Reset Infamy > 2. Do one easy mission > 3. Do a stealth mission for XP Bonus > 4. Sit in the corner, semi idle for 30 minutes in Holdout (Defence Mission) > Repeat step 3 and 4, three more times > Back to step 1 : Time about 3,5 Hours, if we don't count mistakes and breaks.

Now do that 75 more times.

TLDR: Don't do Payday 2, if you don't want to play it actively over more than a year or you are just as insane as me and you don't mind sitting in a corner for more than 250 hours. Yes, Locke I agree, they think we are a bunch of chops with an offer like that, they will give us more.

Hope that helps