How much actual space do you have if you don't mind me asking?
My situation - our patio at one end (where the patio has a couple of steps going down to the garden) only allows for me to have a 4ft front-to-back set-up of any kind. However; further along to the left near to the house I can have a 'deeper' set-up. It's for this reason that I think I'm still going to go for a shed plus aviary (or 3ft run) because I can then have a 6x4 shed with a 6x6 run - I wouldn't be able to do this with a Kennel set-up and I'd prefer a 'squarer' run. I'm hoping we might be able to have a slightly bigger run than that but I'll have to do lots of measuring up and check lol.
Just thought I'd explain my decision process in case it helps you with yours!
I still have to decide between a full-height aviary and a 3ft run - I know which I'd like but John would prefer a lower run. So still have to make more decisions yet!