Every PEI plate I have bought for my Aquila have been 235x235. As for suggestions,I have tried various brands,and to me,one didn't work any better than the other,had no issues with any of them,they stuck fine. Just depends on who slaps their name on it. This is the one I'm using now...PEI Plate
I got this one from Amazon and it works amazing.
HICTOP Flexible Steel Platform... https://www.amazon.com/dp/B08PFHBR2D?ref=ppx_pop_mob_ap_share
Amazon '235 PEI' the base comes with the plate.
https://www.amazon.com/gp/product/B08PFHBR2D
https://www.amazon.com/gp/product/B09X53YHHD
https://www.amazon.com/gp/product/B0B3XK5NKH
I have this 2 sided that came with the base https://www.amazon.com/gp/product/B09YNN2Q15/
They're on Ali as well.
I have 2 different glass, G10, the stock PEI, and the double sided. I only use the double sided PEI, side depends on how much I need it to stick. The smooth side is insane but gives a gorgeous finish. The textured usually releases by the time the part cools.