I have been away from poker
for a long time, considering getting back into it semi-seriously.

I used to put in heavy hours into micros and some small stakes online.
(25NL 50NL some 100)

I'm not sure what stakes I should return to. Do you think
I should start at 10NL and grind up from there

I know each stake level has its own metal/skillset. However
not sure if I should waste too much time on the micros anymore.

It depends on what your goals are. Do you want to make poker your primary income source? If so, micros probably aren’t going to do it. Do you want to play as a hobby or for some side income? In that case starting at micros should be okay. In any case, generally you want to have a bankroll of at least 25-30 buyins to minimize your chances of going broke. If you’re starting with a small bankroll of say $500, then no higher than 25NL is best. You need a larger roll if you don’t want to start at micros.

Start at the lowest stakes to begin with, add $ for higher stakes if you end up doing well.

20-40+ buy ins depending on risk tolerance/winrate/std dev/ability to reload

Thanks, I guess to reword my question:

Are the micros worth the time?
Micros are great for learning, but I think it gets
to a point where it's like, there's diminishing returns
on what you learn. And you also go through lots of
psychological turmoil for little profit.

Depending on how long the "long time" you have been away from the game is, then yes, it may well be worth it in the case you learn that the game is a bit tougher than it used to be. If you are currently break even at 10NL and a steady loser at 25NL, which stake is it better to find that data out at?

Im just a nobody but I agree with them, there answer make the most sense. I would start some where low and see how I would be doing there and then work up till I felt like there is a challenge but nothing I couldnt over come. Then keep progressing an find that spot your most comfortable at and winning.

What are your goals? How hard is it for you to reload $250 if you bust?

Ive always had very aggressive bankroll management playing micro and small stakes. The goal for these stakes should be to improve and move up to higher stakes, not income. IMO a bankroll is really only for someone relying on poker for income, so they can keep real life money separate from poker money. Everyone else has a poker budget.

I would deposit $250 and start with 25nl to get a baseline on your skill level. Move down to 10nl if you get down to $150 or so, and take a shot at 50nl if you get up to ~$350-$400.

I think the most important thing to move up is don't be afraid to lose a couple buy ins and drop back down right away. Its important to get the reps.

That's 4 stacks lol, might as well just start at 10nl then

Yep its aggressive but you should still get enough hands in to get a feel for that stake and if you belong. Lose 4-5 buy ins and drop down, win 4-5 buy ins and move up.

You dont need traditional bankroll management at microstakes, especially if you dont rely on it for income. Sure if you are a 12+ table microstakes player grinding out a wage with volume, then you need to be conservative, but OP doesn't seem to be in that position.

Unless reloading with another $250 in a month if you bust is off the table, be aggressive with the bankroll, get better, and focus on climbing. Once you climb to small stakes, you can be more conservative since the competition is tougher and the bankroll becomes harder to replace from real life.

4 stacks can and will be 4 hands in some cases lol ... it's meaningless
it's so easy to play good and lose 4 stacks in just a few 1000 or even 100 hands

I totally agree with the aggressive bankroll management, but moving down after losing 4 BI's makes no sense imo