Any dob over 10" needs to be in truss configuration IMO for portability, which adds significantly to its cost and basically goes way over your budget after allowing for a couple of reasonable eyepieces.
In terms of optical quality IMO the GSO scopes are a little better. Unlike many people here, I had exposure to some of the early Synta/saxon scopes which had pretty average optics indeed and pretty poor quality control. Since Orion USA became involved with Synta about 5 yrs ago their influence has improved the quality control and standard immensely so they are now both very good. I have used a large number of GSO scopes and apart from one 8" sample, they have all been good (at worst), with a couple excellent. The GSO scopes have BY FAR the better focuser, with the Crayford thats offered on the deluxe version and IMO this is important. It's a pity the silver paint finish on the newer GSO scopes leaves something to be desired, that's easily fixed. My GSO scope is one of the early ones which has a Black Baked Enamel finish with a grey metal primer underneath. I have had this scope almost 5 years with no signs of rust spots. Obvious this quality of finish was discontinued because of cost. I also got VERY LUCKY with the optics in my scope. The mirror is outstanding, several forum members who have looked through my scope could confirm this.