Just replaced my 18 year old system in December and had a similar decision to make. Replaced an '87 Janitrol AC and Carrier furnace. The Carrier heat exchanger had a hole in it the size of a silver dollar.

The decision:

1) Trane 14 Seer R22 w/10 yr warranty - $1000 more than #2
2) Amana 16 Seer 410a w/Lifetime SS H/E and 2 stage Compressor warranty - $900 more than #3
3) Amana 14 Seer R22 - $1000 more than #4
4) Goodman 12 Seer R22

It was a tough decision between the Trane and the Amana. I chose the Amana 16 seer because:

1) the lifetime warranties
2) higher seer rating
3) 2 stage compressor on the 16 seer
4) 410a over R22
5) installer - 2 year labor warranty included

I felt it was the most bang for the buck.

I also received quotes for a Bryant system and I believe a Comfort Maker?? which were eliminated early.