[janoskiss (Steve H)]

Comes down to small differences. I had a GSO 8" and the mirror was excellent. That scope was bought 10 years ago though. I'd assume by now both GSO and Synta have perfected mass production of 8" mirrors, so you've got to look at what else you get in the package.

AFAIK GSOs come with a better Crayford focusser that has a 10:1 fine focus control, while the SWs only have a basic 1x Crayford. That's a significant plus at higher than 200x powers. Different sellers include different accessories. Bintel have a right-angle (RA) finder with their Bintel branded GSO, but I think Andrews have a straight-through finder. RA finder is much nicer once you get used to it (less neck strain). If you combine it with a red-dot style finder (Rigel quickfinder or Telrad are the best), it's bliss.

But don't get analysis paralysis: any of those scopes would serve you well. You can always accessorise them later to your liking.

You will also need a collimating tool. Don't get a laser collimator for your first basic collimation tool. They easily get knocked out of alignment and are unforgiving if the laser is not precisely aligned within its housing. Get a long Cheshire style collimating tool and learn how to use it. Much more reliable and lasts for a lifetime. Cheapest I've seen around recently is the Skywatcher branded one from Andrews for $49.

As far as the scopes holding collimation, both brands do very well, if you do it right and secure the locking bolts properly (you need to keep checking collimation as you tighten them).

GSOs tend to come with better eyepieces - still budget EPs but are fully multicoated, while the SWs are coated/partially-multicoated. In practical terms that means better contrast. AFAIK. Do your own research to be sure.

All I've said applies to the 8" models only. For your first scope I strongly recommend 8" and no bigger. I've had 8", 10" & 12" Dobs, and also used 6". The 8" f/6 Dob is really a sweet spot, best overall fr ease of use, portability and plenty aperture. Solid tube is fine and fits in a car, unless you must have it all in the boot of a sedan. Solid tube will also be more durable and keep your mirror better protected, especially if you use your scope around other people.

PS. Don't get a black tube model. Gets very hot in the daytime if you happen to leave it outside (or put it outside early to try and get it to cool down before sunset) and is less visible at night. White on the outside and matte black the inside is what you want.