I would recommend Bluemels' for the grunt work of tilling. You probably want to supervise more closely if they are going to amend the soil, and you want to stick your nose in a lot of they are going to do some/all of the planting.
They did some work for me. They tilled for me and laid a brick walk and did a nice job.
Soil is nicely worked up: down about 10 inches across the area. Under 10 inches: solid clay....
The original plan/layout they drew up was sketchy and ambiguous: I drew one with graph paper, and got the big items exactly where I wanted them, but the perennials they put in were sometimes odd: A tall variety when I asked for a short, and vice versa. Details, details.
Overall, though, I would give them a B+ : I couldn't have done all that in 2 days like they did