I had the first A/C estimate last week. It's for our townhouse (Ft Lauderdale) that is 1200 sq/ft. The first place only does Lennox and gave us these quotes.

Option 1: $3676
Outside Unit: 13ACX030 (15 SEER Effective)
Inside Unit: CBX27UH030 (2.5 TON)

Option 2: $3912
Outside Unit:14ACX030 (16 SEER Effective)
Inside Unit: CBX27UH036 (3 TON)

Option 3: $4028
Outside Unit: 14ACX030 (14.5 SEER Effective)
Inside Unit: CBX25UHV030 Variable Speed Motor (2.5 TON)

Out of them, Option 1 is the least amount.
Option 2 he said is the most energy efficient, since its 16 SEER.
But Option 3 has Variable Speed Motor for the inside unit.

Between them, not sure which is the best option. All of them use the Merit line for the outside unit, but #1 and #2 an Elite for the inside, but #3 uses the new variable speed, but it a Merit. I not sure if variable speed makes much of a difference.

Just need to go with the option that will be good quality and use less power. We currently have a 10 SEER 2.5 TON Rheem from 2000 that is killing us.