Virtual Reconnaissance

It is my intention, in the coming months, to dive into as many different virtual worlds as possible. Thus far, I have a pretty good take on Second Life. I have recently dug into Dofus, Multiverse, and Active Worlds. Next on my list are Entropia, There, and somehow Forterra and Open Croquet. I’ve pondered getting into World of Warcraft, but I just can’t bring myself to commit to the subscription fee.
I really wish to answer the following:
Which will emerge as the leading business training platform?
What are their capabilities from a training and consulting perspective?
Which is the easiest and most cost-effective to enter?
Which captures my imagination and holds it the longest?

In a nutshell, what are my findings thus far?
Second Life:
+ The most potential, Very beautiful graphics throughout, Relatively good security and privacy features, Quick to pick up on the interface yet feature-detailed enough for the tech crowd, Good interaction and communication features, Strong micro communities throughout.
– Depending on where you visit you can run into a lot of childish jerks, Oftentimes laggy (pieces of landscape, body parts, clothing, movement missing or slowed), Lack of “Quest” or “purpose” can cause frustration.

Dofus:
+ Silly clean RPG fun, Clever artwork, Mildy entertaining storyline.
– This is pretty much a kids game, People in-world hardly ever communicate so no strong communities, Graphics are a bit lacking.

Active Worlds:
+ So far I have found none
– Orientation left me with no useful information, Communication better than Dofus but lacking in substance, Graphics much better visually than Dofus but far under those of 2L.