We love the look of the Kohler vault sink series for it's squared edges.
http://www.us.kohler.com/us/Vault™-33-x-22-x-9-5-16-top-mount-under-mount-large-single-bowl-kitchen-sink-with-4-faucet-holes/productDetail/Under-Mount-Sinks/427700.htm

However, we've heard from folks who have it that food gets caught in the corners of the basin. Does anyone know of a sink that has square corners at the counter level but is rounded in the basin? Hope that makes sense!

Or, can we use a rounded sink but cut the counter square?

Thank you!