IMO this would be a no-brain-er... 500c SPORT 5 speed
Didn't like the Pop seats either and wanted heated seats too, so I went aftermarket.I test drove a 500c Pop (want a manual) on an 81 degree, sunny day. If they offered the Sport I'd likely already have a Fiat today. I just don't care for the seats in the Pop. While I prefer the leather seats, the Sport seats were nice enough that I'd manage.
I also wish they offered the Lounge with a manual (they do in Canada) or a leather option on the Sport. I suspect the high percentage of manuals selling may lead Fiat to change the mix next year.
For now, though, I'm using it as an excuse to wait for an Abarth, which should have both a manual and a leather interior option. I'm leaning towards a hardtop, if only because I don't want to think of the price for an Abarth 500c with leather (ouch!).