Currently a 12Y reservist , thinking of going active. Should I stay 12y or go 35g . Also thinking of 37F. Any input on AIT or duty stations?

As a 37F on active duty, you will be forever stationed at the black hole that is Bragg.

I loved AIT as a 35G and I love the job. 12y's work with 35G's all the time and do similar work so the transition should be easy if you are able to get 35G. Plus on the civilian side the pay is wonderful.

Do what YOU want to do.
With that being said...
Get a good grasp of the 12Y MOS before you transition, it will help you out no matter what decision you make.
12Y you already have a basic grasp of what you'll be doing.
37F is a pretty cool MOS, but if the selection process is still the same as it was, it will be extremely physically intensive. 37F is a part of the SF community, you'll need to be/remain in top physical shape.
35G is a good MOS to get into. If you have GIS knowledge already, you will be an asset wherever you go, but you will truly be an asset for a COCOM. Having knowledge and experience in both Geospatial fields will also help you out significantly when you eventually end up in the civilian sector.

All active duty 37F, are, or were, stationed at Ft Bragg. Yoi can choose any duty station you want, i asked for Vicenza, but you only get Bragg.

35g. Easier to get promoted. My squad leader was a 12y and he hit a promotion wall. Plus being in a MI unit is better then being in an engineer unit

You very likely will not have a choice, or many choices. You'll need a TS and an open class seat in a notoriously small MOS to go 35G. 37F still requires you to pass their selection and airborne school for active duty, unlike the reserve 37F.
When you get to MEPS they may very well tell you that they don't need any 12Y and you will have to reclass to whatever they have available.
I would recommend not to stick to closely to any particular MOS, but more like a career field. For instance, they may tell you that there are no more class seats for the next year for 35G, but they have 35N or 35S. Look at a career field, versus a particular MOS. Most MOS fields combine at E7 or E8 anyway. If you are hoping to stay till retirement, becoming a Senior NCO, Warrant, or Commissioned should be a goal.