Most of them are crap and I've been shunning them - until now.
@enforcer48 told me about a couple bots which he tested and found to be useful - especially for those of us who still have significant trouble in operating funds...

He introduced me to @thundercurator who for a 0.121 SBD investment, pays out 0.36 - when I did the math (even after deducting for curation, etc) it showed a very good return on investment (ROI for the more savvy among us.) This one runs about 3 days behind, so remember that when asking for an upvote from him. (Although he did refund me when he couldn't get to one of mine in time.) One thing I really like is that for the 0.121 invest (instead of 0.120), it's a silent upvote, no commenting.

Also, there is @treeplanter who actually do some good for the world at the same time! You pay in what you can up to 0.25 SBD. When I pay in the maximum, I get a 0.53 upvote. Again, once doing the math, it was a good ROI, so worth doing. They also put out a daily bulletin featuring the top contributors as well as where you were for the day. This bot does comment on your posts, but it's for a good cause, so I don't mind so much.

Then there is @zenbot run by @kaliju which has proven to be a very nice bot too. For my 0.5 SBD (minimum), I get an upvote worth 1.08 or so. Again, very much worth my time and effort - and makes my post look so much better! If he notices his upvote has eroded too much, he'll make things right with a 100% upvote (1.53 or so at the moment) to make up for it.

I'm also playing with @bumper right now - who were top rated in several articles I read. That one has a 1-2 day lag at the moment and I haven't had the time/funds to test it completely. Within the next few days, my cash flow should be a bit healthier and I'll test them a bit more thoroughly.

I did try two of the cheaper resteem services recommended in one post and neither of them did anything worth paying out for, so I definitely would not recommend these.

There are a few articles out there from 2018 even, which talk about some of the different bots that are worth trying. It does seem clear that with a little research, you can do a bit more for yourself than even @dustsweeper proposes.

(I do love SBI shares though.)

Checking out what whales use repeatedly is probably a good marker. They can afford to lose out from time to time, but many of them consistently go back to the same bots.

just a few thoughts.
I'll probably do a post in a few weeks.