If you can find Kai scissors, we use them to do heavy duty cutting at our charity group. It is the only one where my hand does not get tired and they have cut for a year without an issue. Originally they were put out by Fons and Porter and ours had a red plastic handle. You might get them online. I actually like them better than my Ginghers.
Recently Connecting Threads was clearancing them and you might even get them straight from Kai. Or I also found the Fons and Porter ones on Ebay.