If you are considering Mesa cabs, I would have to say a closed back cab before an open back. Then of their closed back cabs, the Traditional/Stiletto cabs are the tightest because the air volume inside makes them tighter in general.
How does the Genz Benz sealed 4x12 sound in comparison to their ported version? I am assuming that the ported 4x12 just sounds bigger than the 2x12 ported. I am also assuming that their sealed cad would be tighter than their ported one. I am not slamming a G-Flex but he asked for tight.