How to pick the best air-conditioner?

One of our existing air-conditioners is about to die soon.
So we need a replacement. But which one?

Currently we need a smaller unit for the second floor.

Carrier system
One of AC installer companies recommend "Carrier" system:
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Cooling Capacity : 22000
Heating Capacity : 21600
SEER : 14.5
EER : 12
HSPF : 8.2

Heat Pump Carrier 25HCE424A003
-10 year parts limited to original purchaser upon timely registration (otherwise 5 years).

Air Handler Carrier FV4CNF002L00
- Variable Speed

Auxiliary Heater Carrier CE0501N05

Thermostat Carrier TP-WEM01
- Wifi Capable.
- 5 year warranty if registered in a timely manner.
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Price (including installation): $5,699


That choice seems a little bit pricey for a small AC unit. But what do you think?

Update:
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http://www.homeadvisor.com/cost/heating-and-cooling/install-an-ac-unit/
Most homeowners report spending between $3,710 and $7,140 to have air conditioning installed. This price is more typical of a central A/C unit installation rather than a window central air conditioner addition which typically averages about $300.
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