Don't know, have tried them all and SMF is the best for me. and the 2.1 looks like the right move so far as I can tell, allot of things are nice to have but not needed. If you have something good, it's best to just make it stable/secure and a little more flexible, if possible, and if something is not broken , don't fix it.
It's not a forum (only) ( it's Not a Blog only) but it is as I can see the most versatile community system out there, that portals and mods can be added on. I feel if you change things too much you may screw up and already good thing. ( i have seen this forum system used in so many ways already)!
I don't know how everyone feels, can not possibly know, but if I visit A vbull site I know as soon as the pages opens, if I visit a wp I can usually tell right off, and so on and same goes for most.
If The SMF team sticks to a solid base and makes some improvements on the way of looks and feel (or features) fine, but after you have a Kick butt system and great foundation to build on these are more important, to me anyway.
Some of the other systems out there are very hard for the topical user to navigate how to set up and use the system just to find it still does not do what SMF can do

some you need a webmaster to set-up run and maintain!
Not to mention the fact that some themes are and look better on SMF that some have done, and are working on as we speak.
Again I like to say you are doing great, and please don't get distracted trying please everyone, cause it will never happen!
and Thanks!
regards,
Maxx