Well I don't have a whole lot of info on Marquis and the info I have does a comparison between the Coleman C461-deluxe and Marquis Wish LX. My info on Marquis is a few years old so the Quest may have been added since then.
The Coleman 461 is 78x78x35 It has 2- 2 H.P. 2-speed pumps powering 26 jets. It holds 300 gallons takes a 50 sq,ft filter and has a skimmer basket and first fiter option. This is an amzing feature that will catch most of the debree like leaves and grass before it gets to the main filter.
The spa has a powerworks M-7 control system which did away with pressure switches that could stick open or closed. Coleman uses thermol-lock insulation, solid ABS pan bottom, and a Galvalume steel frame
This spa has a lounger and a therapy seat with the comfort collar neck jets. If memory serves me, pump one runs the lounger and the seat in the opposite corner. Pump two runs the therapy seat, the foot jets across from it and the seat right next to it. You know whats nice about that...If you're the only one in the spa and the lounger is your favorite spot, you don't have to even turn pump two on, or the other way around.
I've had the chance to soak in this spa and it has some awesome therapy. With the two speed, big pumps and added air contols, everyone in the spa can taylor their experience.
I would reccomend that you wet test both spas. If you're tall and long waisted the comfort collar seat in the 461 could be a tricky fit.
The 461-deluxe has been a good seller for us. The warranty is five years parts, plumbing, electrical and labor, 7 years surface, and lifetime on the steel frame.
As far as quality, you can't go wrong with a Coleman. I've heard good things about Marquis as well.
Good luck and let us know how the wet test goes.
Spahappy