Foundry is outstanding. My groups moved to it after being frustrated with Fantasy Grounds and Roll20. Only parts of it are open-source, but I don’t mind in this case. It can be self-hosted, only one copy is needed, the price is reasonable, and the money goes to a small team of independent developers rather than a big corp.

(My one notable criticism of Foundry is that their official support community is on Discord, which I won’t use. This hasn’t kept me from using the software, though. There are plenty of other users out there, so it’s pretty easy to find information when I need it.)

We use Mumble for voice chat. Open-source, lightweight, cross-platform, low latency, good noise filtering (RNNoise), great sound quality. You can self-host, or pay for a super-cheap hosted server.

For the sake of completeness, here’s a VTT Wiki:

http://rpgvirtualtabletop.wikidot.com/the-vts

A few random virtual tabletops that I bookmarked during peak pandemic:

https://www.diceright.com/

https://www.mythictable.com/

https://www.planarally.io/

https://new.tableplop.com/

https://tarrasque.io/

https://www.shardtabletop.com/