I've used both Fantasy Grounds and Roll20 for 150+ hours each. Both work well - neither one is a bad choice, but I prefer FG for a couple of reasons:
1) I like the UI better in FG. For example, navigating the character sheets are easier. FG sheets are small with lots of tabs along the side so it is easy to click to exactly what you need. Roll20 sheets are large and I am often scrolling around to find what I need; spells are on a separate tab but the tab button is on the page itself, so I find myself scrolling to find the tab button for the spell page, then scrolling on the spell page to find what I need.
2) FG has a lot more automation built in. This gives it a bit more of a learning curve, but it is nice once you have a little experience. For example, you could apply a "rage" effect to your barbarian with one click that automatically adds the bonus to damage rolls, applies resistance to incoming damage of the appropriate types, remembers the advantage to Str checks, and expires after 1 min.
3) Roll20 is "freemium" but you will likely end up paying more in the long run for a subscription and the content with Roll20 than with FG.
Whatever VTT you use I'd recommend discord for voice chat.