Virtual gaming table recommendations?

As some of you may know, jordangreywolf ran the first Avatars campaign a couple years ago. It was fun, and great to get the gang back together.

Avatars was the most popular virtual reality game of the 2060s - a game in which children and adults would create their own avatars, imaginary friends that they could take on quests in a virtual world overlaid upon the real world. That changed in 2065, when a series of brutal murders culminated in a reality-shattering explosion in their California park on the eve of its grand opening, and Avatars was shut down for weeks. People told strange stories of holes opening up from reality into VR, of falling into the strange worlds of the Diadem, or being attacked by monsters that had somehow escaped into the modern world. But how much of it really happened? Only a few people know, and they're not telling.

Now I'm looking at running the follow-up for the group. But one thing that Greywolf did for the first campaign was to illustrate battles by providing JPGs with a map and players (and NPCs) placed on a grid on the map, giving everyone a good idea where exactly they were. That's something I'd like to do for this campaign as well, but it seems to me like there must be a better way than making maps in MS Paint, saving, and uploading them repeatedly.

A little Google-fu brought me here, a list of "virtual tables". I investigated a couple, but I'd like to know if anyone's tried any of these and what their opinions are.

( Specific reviews cut for length.  )