I live in a flat roof row-house in DC and need to replace the package unit on my roof that heats only the 2nd floor (approx 800 sq'); my current system has a cracked hear exchanger. We've been visited by nationals and local independents but no one has recommended the same machines. What direction would you recommend:

RUUD RRRL-C-024 (16 SEER residential, limited Lifetime HE)
Lennox 15GCSX-024 (15 SEER res, 20 yr HE)
Rheem RRPL (14 SEER)
Rheem RQPM (14 SEER)
Trane 4VCC3024BIO64A
Trane XL14C (14 SEER, 20ys HE)
Goodman GPG (15 SEER, 20 yr HE)
Kenmore (14 SEER)
Carrier (14 SEER)

We are leaning towards the Trane XL14C (14 SEER, 20ys HE), simply understanding the value of a long warranty on a heat exchange and a stainless steel HE. Any other thoughts on any of these machines would be greatly appreciated. -O.