PETG is my goto filament. Don't even use PLA as it's too brittle and can't handle heat. I have PETG really dialed in on my Creality K1 Max so all my prints come off great. And PETG is darn near the same price as PLA on Amazon.
Regarding the vents, I'd say Acrad has it right to use PETG. PETG is a little more flexible without snapping and can handle higher heat.
One last note is that how strong a part is depends upon how you orient your part on the build plate. Example: if you're printing a rod vertical on the build plate, considering that the print head does layer upon layer stacking, you'll have very weak beam strength on the rod. If you print it flat on the build plate with the print layers running the entire length of the rod, your beam strength will be much stronger.
So if you're printing your own vents and they're not holding up, try using PETG (as Acrad had) and change the orientation of the print on the build plate of your printer, maybe tilt it 15º or so. Yeah, you may use more supports but it may also be stronger.