Heucheras winter kill is usually because they are too wet. If the area is soggy, they will die. Usually our ground freezes and stays frozen. Last winter was unusual to say the least. Melting snow gave some areas very wet soil, which is fatal to many plants. 

You may want to plant them a little high. Make a mound to keep the crown an inch or so above the surrounding ground, but mound the soil so the crown is at dirt level. You are in effect making a little raised bed. 

I grow a lot of heuchera and really don't see a survival difference in different varieties. "Palace Purple" has been around for ages and does well for many people, but the newer varieties are fun to try. 

Sorry you lost so many last year. It is a frustrating part of gardening.