Hiya!
Tempted to put FGII, but had to go with Tabletop Simulator. The main reason is simplicity and no real "learning curve" to speak of. I mean, it's a virtual table top...literally! You can customize what you want/need, roll dice, move mini's, have simple 2d maps...or full 3d maps with dynamic 3d lighting, sound etc. You can import your own PDF's for use at the table, hide stuff from the players or specific players, etc. You can, effectively, play ANY rpg you want, with little prep. You can even create your own Character Sheets with automated functions if you are so inclined (and simple sheets are dirt simple). In short... it allows the GM to create and customize what they want for their game, and it allows Players to just log in, and start without needling to learn, well, much of anything. It's all right there in front of you; table, mini's, maps, character sheets, rule books, dice, etc.
Seriously. Anyone who has any interest in a completely "game agnostic" VTT should at least give it a try. There are a TON of custom made games, tools, items, etc that are on the Steam Workshop; just find one you like, hit "Subscribe" to it (free; it's just a term), and it is auto linked to your TTS. Click on it in your TTS screen and it loads in. Biggest bugaboo with that.... links to some of the assets can get broken over time. But if/when you do it yourself, or save stuff to your own HD...no worries.
^_^
Paul L. Ming