Here is my take..
TSF: This is a totally different experience with a lot of new cool features. They don't make the phone work better really.. they just just allow the interface to look different. It's fun but not really what I liked after playing with both for a while. Not to mention TSF is expensive. Also the widgets are limited and really more annoying than anything. Sure they are fun for a little bit but after a while they get kind of annoying.
Pros: Great interface, highly customizable, very different than the norm.
Cons: Expensive, learning curve, and bland widgets.
SPB: Very nice, I use this as my daily driver. It's really easy to use even the very first time and the 3D effects really set it apart. I can't remember the price but it wasn't that much.
Pros: Beautiful, great widgets, easy to use.
Cons: Not quite as flexible as TSF, app drawer for this one will have you missing the default ICS app drawer.