I actually LOVED the beginning to SOS! So much so that I made my wife and kids stick around when I put the DVD in last night when I got home. I remembered being in "awe" while seeing it at G-Fest. This is also the first movie since the original Mothra and Gvs.Mothra that Mothra didn't bore me to tears.
But really, I can't say which one I prefered between GxM and SOS. They both kind of tie and work well as a whole, IMO.