I know this is kinda of a relative question… I was curious what are the best habits that you would recommend?
Here’s some that come to mind…
I’m trying to figure out the best place to focus my attention.
Well, I don’t really think of it as forming habits - I’m only doing the things because I’ll have to pay if I don’t, so it’s not really a “habit.” It’s just a way of making myself do stuff that I really don’t want to.
So I don’t really recommend any “habits.”
But, here are my current favorite things for beeminder goals:
(A) The best habits are the ones that you want to cultivate, so there’s no universal list.
(B) You noted this fact in your post.
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(C ) You’re asking for input to help spark your own ideas.
In that light, here are some of my most rewarding habit-cultivating goals:
Brush my teeth every night. I had a Beeminder goal for this until it became a habit; then I archived the BM goal. I still brush my teeth every night, two years on.
Daily steps. I started tracking these in January 2019 and have consistently raised my daily average from a slothful 2k to a decent 6k a day. (For all of 2019 it was even higher—more on why that was so successful here.) This is probably a “habit” closer to Zed’s description; I’m pretty sure I’d lapse if I stopped using my tracking tools.
Reading. I don’t need a goal for the actual reading; I’ve always read lots. The habit I’ve cultivated is keeping track of what I read. Thanks to Beeminder, I now have a list going back almost three years.
In terms of philosophizing about what best habits I could cultivate… well, take a look at my goal gallery. Actually, that’s a great idea to answer your question, I think—browse through other people’s goals. Start at the Featured page, and you can click through to any person’s gallery page. That should give you a wealth of ideas, plus if you tally the repeats, an idea of how common some potential habits are (which is one possible metric for evaluating “best”).
My current favorite is my morning pages goal. I write three pages (or equivalent) every morning. No restriction on what I write, just stream of consciousness a lot of the time. Gives me space to process and think that I don’t have otherwise.
Some folks who encounter Beeminder and become enamoured with it get very wrapped up in using Beeminder to become better at achieving their goals, to a point where it can get very meta.
“I want to read more books so I should get better sleep and a better job and never watch a video on the internet and and and and … So that my life will be a perfect slate for me to finally do the reading I want to do.”
Sharpening your pencil is good, and thinking about it is good, but don’t forget to use your pencil too! Even a full pencil makes a mark.
Adam, stop being an old man who speaks indirectly and then laughs at himself a lot 
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I suggest throwing in a goal that is directly something you want, rather than something that will eventually make it so you can start something you want.
I can’t speak for others, but I’ve actually found this to be an incredibly useful exercise. My thinking-but-not-doing, navel-gazing often occurred before I began keeping a meta-account of all my ideal habits.
Now when those thoughts arise, I either a) enact, b) figure out what’s stopping me from enacting, or c) disregard the thought.
So my answer to OP would be that the best habit you can have is a metahabit! Or rather, a scheduled (and public) review of the habits you’d like to do vs. what you’re actually doing.
If you say you want to read more, but you have to declare that you haven’t yet, week after week, you eventually break. You have to come to face what’s really going on, and what’s really stopping you.
Of course, this sort of systematic repetition is probably crazy, and I’m too far gone to realize it is. 
But if you try that, and it doesn’t work (and if you’re me, it won’t) - it’s worth considering why it doesn’t work, and what goals you can put in place to get to a point where it will.
Like if I’m not sleeping, eating, exercising, and meditating - literally nothing else is going to work. Nothing.
Nope, it’s totally normal and very human, and it’s the first step (as you noted) to realizing what you really need to do.