Online MapTool, play with others too.

UPDATe; Owlbear Rodeo might be best. SIMPLEST, and mostly free. And ... dont have to buy a bunch of modules that you are stuck with. Just do rules and monster stats outside it.  

https://www.reddit.com/r/MapTool/comments/ialkpr/need_some_advice/

If all you want is a battlemap, and you manage initiative and HP on your own (like you would in person), you don't need to mess with macros at all.   

     Yes. It is. Very much so. I tried both initially and found them terribly confusing. Then I came across this guy's youtube channel and it just clicked. Maptool is simple (save for macros, I still don't get those). It's easy.

https://www.youtube.com/playlist?list=PLD4i-ngGs9thEXoHaxzRqD0b3zWcmpAOn

I watched a handful of the videos (about light, fog of war, vision blocking layer, tokens, etc.) and felt competent enough to start DMing right then.   

>>It depends on what you want from it, and what you're willing to put into it.

The biggest advantage for Roll20 is that because it runs in a browser, it "just works" without much in the way of technical knowledge.

MapTool, on the other hand (assuming by "online" you mean remote players), requires you to set up some form of port forwarding on the server. This can be simple, and often is, using the "Use UPnP" setting when you start the server. But not all routers support that, or work right with it, so sometimes you have to do it the hard way.

Other than that, the most basic functions, share a map, and drop some tokens on to push around, isn't much different than any other VTT. Where MapTool really shines is the macro language, which can do pretty much anything if you put enough effort into it. If you play a popular game, like D&D, there's a good chance someone has built a framework for it that you can download and use without too much effort.

But if you want to customize it, you have to learn the macro language, which is complicated, not very intuitive if you have no programming experience, and can be very, very frustrating. However. . .

The other place MapTool really, really shines is the support community. The forums and the Discord channel are both very welcoming of newbies, even newbies with stupid questions they've answered a million times already, and they are genuinely helpful. (And the devs are frequent participants, so if you run across a bug, they'll get it fixed quickly.)

So the answer is, if you're willing to put some effort into learning how to do stuff more complicated than "map, tokens to push around," MapTool is a good choice because you can do almost anything. But it can be a steep learning curve, so it requires some effort.