Might be for a narrow category, but this option was great for my group. If you need a visual tool to complement Discord or Hangouts audio and you don't care about cruft like markers or rules tracking, there's an online whiteboard tool called Twiddla. It's light, free, and has a simple dice roller and graph paper built in. You can also bring in images and webpages to draw on maps. It is not a VTT, but for groups used to free hand maps and a whiteboard, it does the trick without any headache.