Hi Wassaby
It looks like you have been given plenty of advice here and everybody has mentioned there favourite board to use in chop, but here are my thoughts on what to look for in a good freestyle board for use in chop.
Freestyle now is all about pop, if you cant pop big you cant do much. Don't let people confuse you with the boards ability for load and pop, with its ability to hold an edge for a big boost, the two are different.
A flexible board will feel more comfortable in the chop, and you will still be able to boost hard, but the flex will reduce your pop, so you need some stiffness.
Go for a board with more rocker, the rocker will suck the board onto the water in chop, and allow you to load and pop without skipping out as you load.
The best freestyle board for chop is not going to be the most comfortable, but again rocker will help, it also helps landing off axis. Thick chunky rails will also help stop the edge catching when off axis in chop too.
I dont know anything, the Naish boards but if you are trying the monarch, it may be worth looking at the Dub too, seems to have a bit more rocker.
These are my thoughts anyway, hope this helps you choose a good board, good luck