I would like to ask the Pros on their opinion on a new 2900 sq ft 4 BR. home I did the electrical for but now with two weeks before sheet rock, the A/C contractor is too swamped to get it done in time so the GC & I were looking to install the system(s) and have him sweat and charge it. I am a licensed electrician & oil burner tech that does lots of HVAC controls residential & commercial in Boston.

The last home we built was a 3 zoned, 3 ton 2300 sq ft home that had a 2 stage vari speed American Standard split with natural gas hot air in the attic.
Every home the GC builds has 6" exterior walls and nice low e windows and the folks that bought the home are very pleased with the unit and are amazed at their low energy bills using it.

The new home is bigger but built the same but there is no natural gas on the street and the GC does not care for oil heat so a 500 gallon propane tank is going in to feed everything with a flame and my supply house only sells Goodman and the GC want a consumer recognized name brand to boast.

"The Question", what would be the most practical and best bang for the buck? 1). Having two 2 Ton / 70KBTU Propane splits, 1 in the cellar feeding the first floor and 1 in the attic feeding the second floor and I'm thinking zone motors to defer the returns from sucking from the ceilings during A/C mode and from the floors during heating mode...or
2). having one 2 Ton A-coil on a 150K propane hot air furnace that would heat the whole house but only cool the first floor and another 2 Ton evap fan box in the attic with high velocity flex to cool the second floor, my idea, but also 3). have 2 - 2 Ton compressors or is there a popular name brand unit that would have 2 - 2 Ton Scroll compressors built in to save space outside, time & money?
4). Having done many systems for a big Boston company, I like Carrier best, American Standard 2nd then Trane 3rd and falling fast but would like the opinions of the Pro's on the cost effective way of bidding this job with high end stuff and ideas on zoning the supplies & returns, the big family room has a vaulted ceiling with an exposed open hall way to the master sweet over the 2 car attached garage.
Thanks for your time, AL