Honestly, the BEST way for you to decide is to lay hands on both. It is absolutely personal preference, since neither will "outperform" the other and both are quality pieces.
I have an ErgoGrip on each of my AR15's except one, which wears the Hogue.
I have medium-large hands, and don't like skinny grips like the A2 or TD, and the Hogue, while thicker than those, is still skinny to me.
The Hogue I have is on the "wife and kids" rifle for their smaller hands, but the Ergogrip just feels right when I grip it.
Both are good, one will most likely feel better than the other to you... But which one is up to you.
ETA: I have tried the EgroGrip "Rhino" (plastic) and it is "skinny" in the back as caw375 mentioned, BUT I have not had the same issue with the SureGrip models.