I love them both, Bear. I can't really find a negative thing to say about OSG though I prefer OLG.
Why do I like OLG? Well, mainly because I think Sakai OpenLife is working his ass off to make a stable environment that will not mirror OpenSim worlds or Second Life. RealXTend is feature wise not always the same as OpenSim. Now it is based on OpenSim but I hear soon that won't be the case as much. Maybe elements, but it will have it's own thing going.
Sakai's motto is stability before everything. The main reason the beta tests of RealXTend in a actual virtual world are taking more time then before is because they are making sure it is as stable as possible before showing it.
Remember.. avatars will be a different Mesh, objects will support Mesh.. this will not be a mirror image of OpenSim.
Now.. advantage prime of OSG is that you can connect your own standalone pretty cheap as Adam pointed out in another thread here. Joshua had a region going.. likely still does and it was set up pretty easy from his account. This is not available in OpenLife right now. You can get a region for about 80 bucks (includes first month tier) and around 59 bucks a month. At least that gives you something to compare costs with hosting your own.
So.. which to go with. Try them both. I suggest you try
OLG when the beta starts though because seeing it now is not much different then seeing OSG or any of the others. Beta is when it will shine.
As Flip said in another thread.. stability is not ready for prime time. Either way you go (or even if you go elesewhere like 3RD Rock, TribalNet, etc) you need to be ready for crashes, server restarts, lag at times, etc. That all comes with Beta. Really, the correct term is Alpha at this moment.
It is totally for the adventurous and hardy ones among us.
Don't make a commitment yet.. just sign up at both grids and check them out. In OLG's case hang out in the chat room to meet some people. Sometimes it is slow in there but often it is pretty active.