The first guy is right, you want to match the output as closely as possible. A little extra capacity over your calc is a good thing too. The other will be oversized for your ductwork and will overheat and have problems. Try get it installed with a genuine 2 stage thermostat and pay extra to run the additional wire for it if necessary. Relocate the tstat if pulling the wire is impossible/impractical and damages the wall/paint. Makes the unit a LOT more accurate/comfortable than the timed on stage switching you get with a standard tstat.
"Cut it twice and it is still too short".