For me personally, while I don't use mine all the time, when I DO use it, I'm cutting a whole quilt. Sort of like making my own personal kit. When I do that, I often end up wishing I had bought the "Studio" cutter.
While I can't speak to the Sizzix or Scan&Cut or other die systems, here's my thoughts on the various AccuQuilt products and the pro's and con's of each:
GoBaby - Pro's - lightweight, very portable, perfect if you're planning to take it to a class. Con's - many of the AccuQuilt dies will NOT fit in this system. (Personally, I would NOT buy this one) Also, if you have hand/joint issues (RA, carpel tunnel, etc) this is a hand-crank system, so might be painful to use. It cannot use other companies' dies.
GO! - Pro's - all the AccuQuilt GO dies (but not the Studio dies) will fit; can cut 6 layers easily, 8 layers with a little "muscle"; Con's - again, this is a hand-crank system, so same concerns for hand/joint issues. Also, cannot use the Studio dies. It cannot use other companies' dies.
GO!Big - much the same as the regular "GO!", except this one is electric, so if you have those hand/joint issues, this is probably your best choice.
Studio cutter - Pro's - has larger dies, can accept all GO! dies (WITH AN ADAPTER); can handle more layers of fabric (which means you get done faster); also can accept other companies dies (again, with an adapter in some cases). Con's - again, this one is hand-crank (but I was told it is not as difficult as the Go! systems); Price may be a factor as well, as it's about $100 more than the GO!Big, but if you are a heavy user, this is the one I would recommend.
Even though I would not consider myself a "heavy" GO! user, I truly wish I had gotten the Studio version.
My comment to those who say they like being able to "trim" down... personally, I find that the cuts from my GO! actually make me be more accurate, especially the HST's, because of the dog-ears already being cut off (it's almost worth the cost just for that alone!). I have most of the strip sets, the Double Wedding Ring (talk about a LIFE SAVER!!!), the Dresden Plate (LOVE this die!!), as well as SunBonnet Sue and her boyfriend, and the Calico Cat and Gingham Dog dies.
Love my GO!