You are in an all electric situation and nat gas is not available?

Here is my general spec sheet for new system.
both outside and inside units should be replaced to have a properly matched system.

15 SEER, 12.5+ EER, 9 HSPF
best matching VS air handler
full BTUs in both cooling and heating for your rated size
R-410a refrigerant(same as Puron)
scroll compressor preferred
electronic demand defrost preferred
thermostat with "dehumidify on demand" feature
staged backup heat strips
new and correctly sized refrigerant lineset
10 yr warranty on parts and compressor

you want a thorough inspection of your ductwork system. size, overall condition, supply and return lines, insulation qualities, leak test, etc.

any hot/cold spot issues in your home should be addressed.

My personal recommendation is Trane/AmStd, Rudd/Rheem, and Carrier/Bryant.

Depending on your location, I would not purchase a new system that did not have electronic demand defrost.

I am not a fan of Lennox brand including their HPs. You have been quoted a builder grade model. The price quoted is much better than the equipment.

IMO

I'm jealous. My contractor didn't give me nearly as detailed of a quote as you got. I didn't even know what they were going to install until one day, Surprise! They didn't even put in the intake for the air handler where I wanted it. I submitted a complaint to the BBB. Now, the contractor is at least acting like they are willing to listen to how I want the system set up. ERGGHHH!

Bottom of the line Lennox system with a typical installation (ie nothing fancy or out-of-the-ordinary). I'd get a couple more estimates. I'm always suspicious of dealers who refer to this as an "investment"!

thanks for the input. i am in the process of getting another estimate now. i would prefer to get a quality system not just a base model. usually i wouldnt expect a base system to be a "quality system". also should the person doing the estimate do a load calc or recommend some one that could do it? the company that did this estimate didnt mention load calc, they just looked at the size of the old unit. again thanks for the info.

You need a load calc performed. Of course I can't see home. What size system are you replacing. Unless you have average building and insulation qualities plus poor windows, I don't see the need for a 5 ton system. A load calc will confirm one way or another.

IMO

Don't let a contractor connect a 5 ton air handler to a duct work system which can barely handle 4 tons of air flow. An over sized AC is a bad choice for a humid climate. Find a contractor who will do a load calculation, or do one yourself.