XC13 is a better unit plus has better warranty. you want the Lennox coil, not a third party evap coil.

what mdl and efficiency furnace do you have? nat gas or oil?

if you want Carrier or sister company Bryant, move away from base series and go to Comfort/Legacy 13 model with matching tin plated coil.

IMO

Thank you very much for taking time to answer. I'm so overwhelmed because I know nothing about HVAC.
I have gas heat.
House is split level around 1800 sq ft
The furnace is I believe Trane brand and installed 6 years ago. Last summer during rebate period we were told by two different contractors that we wouldn't qualify since the furnace is not efficient enough to make the numbers work - thus we were given quotes for 13 SEER AC systems.

Thanks for the hint about brand name coil. I have no idea what coil is but I'll request it. Anything else I should know?

west

I would also get a price on Trane's XR13 13 SEER AC condenser with matching Trane coil.

IMO

Check into the warranty on the Lennox unit. An Elite series unit should have a 10 year warranty on all parts if registered with Lennox. I'll attach more information below. The Lennox is certainly a nicer unit -- the carrier 24ACB3 would be a better comparison.

Here is a link that might be useful: Lennox Warranty Information