June Tailor has several different versions of the Shape Cut ruler now. My favorite is the 12x12:
http://www.amazon.com/June-Tailor-Sh...dp/B000YZ7SJM/
What keeps mine from slipping are grip strips I placed on each side:
http://www.guidelines4quilting.com/G....html#Benefits
The only other brand I know of that has grooves is the Stripology ruler, which is much bigger (20x14). The plastic is harder and less flexible. A lot of people like it, but I still prefer the softer June Tailor. I find it more difficult to place my rotary cutter into the slots of the Stripology, plus its size feels a little unwieldy to me. I don't see any significant difference in slippage over the softer June Tailor mats, although it is supposed to be less slippy. If you do a search for Stripology on the QB, you will find other opinions.
I have used my Accuquilt Go! to cut strips also. Many people really like it, especially for accuracy. I like my Go! for cutting other things, such as triangles and odd shapes, but I still prefer my June Tailor mat for cutting strips.