While many of us have become pampered by DND Beyond's rulebook integration, Beyond Tabletop brings us back to our basics. By removing the integrated rulebooks they allow for every feature to be homebrewed and managed how you and your DM desire. In my findings it is the best tool out there as far as capturing the feel of pen and paper while also giving the versatility and ease of access of the internet.
Roll20 - Roll20 is a suite of easy-to-use digital tools that expand pen-and-paper gameplay.
Fantasy Grounds - Fantasy Grounds is a virtual tabletop to help facilitate play of tabletop-style role-playing games...
Astral Tabletop - Create, host, and manage your tabletop role-playing games — online or in person
MapTool - MapTool is an online, multiuser, networked, graphical, interactive, programmable virtual tabletop.
GM Forge - GM Forge is a Standalone Virtual Tabletop and is a sandbox for GMs.
Rolisteam - Rolisteam helps you to manage tabletop role playing games with remote friends/players.