Mornin' Tony
Heres my thoughts on replacing your system.
One thing to keep in mind is your recent repair-$400. Most times after a repair on an older system like this that company will use that as a selling point to replace your unit for you carrying that cost over to be applied to the new system saving you a little. If this company is one of your options in replacement, see what they have to offer after install as far as what is included-Warranty, Annual Maintenance Services that will be included, discounts on future repairs, etc... Most companies will include Maintenance/Cleaning for a year or 2 at little or no cost to the customer. This is important for those with Heat Pumps and will pay for itself year after year and save on the systems wear and tear.
As far as brands the ones you have listed are all good systems-
Trane and American Standard are pretty much the same systems minus some bells and whistles-American Standard is the Builders model (Less expensive)
York, Rheem, and Trane are very Proprietary in their parts for replacement unlike Carrier.
When something goes wrong, if the Service guy doesnt have it on their truck, you will have to wait until business hours to be able to get a unit fixed. Most Carrier parts can be changed out with out much problems until the correct replacement part can be picked up from a supply house if not available on the truck. Carrier parts are also generally cheaper in repair costs as well.
DONT let the SEER rating sway your decision to much-Dont hurt your head with it. My opinion is not to go with the Best and stay somewhere in the middle. The overall cost and future repairs DONT justify the initial cost at install. IMHO The sales men will throw out there things like Coefficients (refered to as SEER for AC systems), Variable Speed Motors, Expansion Valves in place of Pistons on metering devices, and so on.
For heat pumps myself Id prefer Staged Heat strips (meaning the come in/turn on) one at a time in a timed manner. ( I dont like them all kicking on at once racking up the electric bill if not needed )
Some of the newer system like the Tranes with the Variable Speed motors that have a nice feature which keep the Blower Fan on low ALL THE TIME-Nice to keep an even temp and no stagnant spots in the house.
WARRANTIES--I believe regardless of the SEER ratings or system cost, You will find one thing will be consistant,
Compressors will all pretty much have the same warranty 5 or 10 years, its all the other stuff on the systems that vary. A lot of time it might be 1 or 3 years, (or maybe a "Tail Light" warranty

). Dont confuse the Warranty by getting tunnel vision by the longest one on the system, its the smaller things like the Circuit boards, motors, contactors, etc.,.. that wil eat you up too)
On your thermostat, I would definitely have it replaced. Not sure what is available today but some run strictly off batteries (Dont get that Model) You want one that is powered off the Heat Pump with a Battery back up. The batteries last much longer and will allow you to change them on some sort of schedule instead of dying and dumping all the programming when you least expect it.
Thermostats are not very expensive (Look at Lowes, Home Depot, etc... before talking with you sales guys-Maybe they will throw one in or atleast not rape you on it if you let them know the ones at Lowes etc... are the same and much cheaper

)
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I guess the main thing for me is to NOT get carried away and sell yourself on the BEST current efficiency rating. To me it just isnt worth it now or down the road (Unless you have funds to just chunk around LOL).
--Get a good warranty --Get a good service/maintenance plan --Use a company you are comfortable with and trust that they will have what it takes to fix it "After Hours" --The Brands you have listed are good ones