Apertura, Orion, Skywatcher, are all good. The tube and mirror, at least, come out of one of two factories both of which would be considered good. They differ mostly by accessories and many have identical accessories and sell at the same price.
SOLID TUBE DOBS
Skyline and Apertura are the same scope. I would happily have either of these.
Orion Skyline 12 - $849
Apertura 12 - $879
TRUSS DOBS - COME APART FOR STORAGE OR TRANSPORT
Skywatcher Collapsable 12" - $1015
Meade LightBridge 12 Truss Dob $999
Explore Scientific - Truss Dob that packs up really small - $1200
ADDING SOME INTELLIGENCE
Orion XT12 Intelliscope - PushTo system - $1300
Since you have an XT8 you understand what a Dob is. You likely have accessories, extra eyepieces, added Telrad or other finder, maybe a laser collimator, filters, etc, so I don't know how much you care about the accessories that come with the scopes.
You said no GoTo or tracking but I did list the Intelliscope. It finds but does not have motors. I have the XT8 intelliscope. Can use it with the computer or strictly manual, depending on what I am trying to find.
I don't know about your storage or transportation needs so I don't know if a collapsable or truss are valuable to you. A 12 is going to be bigger and heavier than your XT8.
SIGNATURE: If you wish, you can create a signature (my settings)
where you can list your telescope or eyepieces or whatever you wish. My
signature is at the bottom of this post. A signature helps people help you
because they know what you have. We get a lot of requests from people
saying, "I am new, what eyepieces should I get?" Now we play 20 questions
to find out what telescope they have, what eyepieces they already own, etc.
Edited by aeajr, 02 March 2018 - 12:32 PM.