Teresa, here are a few that I have trialed and come out top of the tough list:
'Borscht' this one is dark year round. One of my favorites for form, color and hardiness. About 9", medium producer of offsets.
'Jade Blush' depending on time of year, shades of green and blushes of pink 9" to 11". Heavey producer of offsets.
'Steel Appeal' seasonal color change from light to dark. About 9" to 11", heavy producer of offsets
'Copper Canyon' this one gets really big. Soil type and time of year can give different results for color. I love this big and tough semps. Heavey producer of offsets
'Picasso' I've had this one for many years, grown it in several soil type, it never skips a beat. The color changes throughout the year are wonderful. Very heavy producer of offsets.
'Wirbelsturm' is a medium size rosettes that makes lovely colonies and show interesting colors year round. Medium production of offsets
'Hatra' gets huge, last mature rosette was 11". Color changes every month, always interesting, medium offset production. '
'Passion Dance' is a medium rosette, makes a nice colony and has interesting color.
To be honest, my favorites can change from one day to the next. Depends on who is shining that day. But all of mine have been trialed for hardiness in my growing conditions.
Can't wait to see which ones other recommend.