I use 1/4" standard plate glass for all my window mods. I've got 4 Antec SX 1030/40B cases that I've modded with 1/4" glass. I personally can't stand all the Chenming (and OEM versions) cases where the window is cut around the side panel latch. I rather do away with the latch so I can have an unobstructed larger window. The latch is cut too close to the edge of the panel, so simply cutting it out is not an option. So what I do is swap the sides of the case around. I take the panel with the latch, and put it on the other side of the case. You have to sand down the plastic latch assembly on the inside of the panel in order for it to fit properly and function properly. Then I take the solid panel that was originally on the other side of the case, and cut as large a window as possible in it. I give up the convenience of the latch on the side the latch was intended for, but 2 thumbscrews are easy enough to secure and remove the panel. I made the window dimension in these cases 17" high, by 13.5" wide. Best price I could find locally was $10 for the glass. That included 3" radiused corners. I just bring a template to the glass shop, so there is no way they can make a mistake.
Glass (no thinner 1/4") is a superior in every way to plastic, except for one........weight, it's way hevier.
Just my opinions above, but I've done a lot of research/trial & error on this. Let me know if there are any questions you would like answered. I have learned so much from forums......I am happy to give back.
If anyone is interested.......I purchased a hundred feet of the proper rubber gasket material to secure the glass. It is the same 2-piece locking gasket material that a lot of the mod sites sell, except this stuff is the proper specs for what we mod. It is slotted 1/16" (not 1/8" like everyone elses) to accept the panel thickness, and 1/4" for the glass thickness. PM me if interested in purchasing.