I use glue. I've had fuel get into a screwed on one. Realized I'd never had cause to take one back off except for that time. And I'd had to repair them where the plastic had failed around the screws. And a glued on one has a bit more strength, less probability to crimp or fold. You can often lay the model on the canopy and the weight is evenly distributed around the perimeter.....

But both methods work great when you do it right.

Since canopy glue works so easy and foolproof, and take almost no technique to get an excellent fit, and takes less time for me..... I rather glue 'em.