It sounds like you are a fairly new diver since you are just now purchasing gear. Why would you want a back inflate? Unless you are going to be a technical diver and need the extra lift or ability to dive with doubles - back inflate BCs tend to force you face down towards the water when you are on the surface.
I have been to the Galapagos twice on the Aggressor. There were times when we were on the surface for awhile waiting on the dingy/panga to come get us.
I dive with the Oceanic Probe (on my second one actually). I am rebreather certified, advanced nitrox, solo diver and have made over 3500 dives and I swear by a comfortable, front adjustable BC!
We also dive in the Dry Tortugas for lobster and on every dive everyone goes different directions and the big boat (Ultimate Getaway) picks everyone up wherever they come up - I have been on the surface for as long as 45 minutes and I sure wouldn't want to do that in a back inflate.
We also own a dive shop and would never put a new diver in a back inflate.
... just my 2 cents worth ... diving in the Galapagos can be extreme, so whatever you choose, be sure you are comfortable with it.
Have a great time!!!