Nope - Trane offers a better base warranty
AS BASE WARRANTY
All Allegiance® and Heritage® products:
10-year limited warranty on Duration™ compressor
10-year limited warranty on Spine Fin™ coil
5-year limited warranty on all other parts
Optional extended warranties available for 10-year coverage on parts and labor
TRANE BASE WARRANTY
Ten-Year Limited Warranty on compressors and outdoor coil
Ten-Year Limited Warranty on internal functional parts
The Ten-Year Functional Parts Warranty extends to the indoor gas furnace, coil, air handler, or thermostat when installed as part of a complete XLi comfort system
Do I go with the 14 or 15 American Std or the Trane and if the Trane the 14 or 15
Go with the higher efficiency unit whichever brand you choose and opt in for the additional 10-year parts and labor coverage, some of the parts are two to three times (sometimes even more) the cost of the extended warranty to replace. If sizing is appropriate look at the payback difference to upgrade to the dual capacity units, besides the additional efficiency you get increased comfort and indoor air quality through greater humidity control and increased filtration.
Also think about replacing the furnaces at the same time (even if there isn't anything technically or functionally wrong with them at this time). It will cost you more to replace them in the future (prices continuously rise w/many manufacturers raising prices in the next month or two ahead of the typical increases with the new model year increase), plus your contractor may have to redo some of the sheet metal transitions to fit the furnaces later and you'll get the increased efficiency from the system now.
If you decide to keep your existing furnaces still go with the higher efficiency units. You'll lose a little efficiency now, but will have the cooling side of the system you want in place when you do replace the furnaces with variable-speed models and there are AHRI match-ups for the 15 SEER units without a variable-speed furnace (ARI - 1422151 - SEER 14.25 - EER 11.7).