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.
Astral Tabletop - Create, host, and manage your tabletop role-playing games — online or in person
Fantasy Grounds - Fantasy Grounds is a virtual tabletop to help facilitate play of tabletop-style role-playing games...
MapTool - MapTool is a 100% community driven and 100% free to use online, multiuser, networked, graphical, interactive, programmable virtual tabletop.
D&D Beyond - Official online toolset for Dungeons & Dragons tabletop gaming
PlanarAlly - PlanarAlly is a web tool that adds virtual battlemaps with various extras to your D&D toolbox.