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.
D&D Beyond - Official online toolset for Dungeons & Dragons tabletop gaming
Roll20 - Roll20 is a suite of easy-to-use digital tools that expand pen-and-paper gameplay.
Adventurer's Codex - A free, easy to use, in-person D&D 5e gaming system for characters, campaigns, and parties.
Astral Tabletop - Create, host, and manage your tabletop role-playing games — online or in person
Dungeon Masters Vault - Extensive tool set for D&D 5e dungeon masters.
Fantasy Grounds - Fantasy Grounds is a virtual tabletop to help facilitate play of tabletop-style role-playing games...