The ones that I got from the LBS "buzz" and vibrate...goes away when I jam a piece of rubber between it and the frame. The $5 Nashbar Allure have a plastic top that looks like might solve this.

What do you guys use/prefer?

My cage has the same problem you describe...I'm thinking maybe the screws aren't tight enough, but I don't want to stress the frame by tightening the screws too much. The rubber idea sounds great though!

I don't think you've done them up tight enough.

How can you stress the frame with a water bottle screw?

what i mean is if i apply too much force screwing em in, it might bend the frame in a bit around the screw point, which I assume over time could lead to some slightly bigger stuff eventually, as you go over bumps.

I tightened them pretty darn tight, and it helps a bit, but I'm at the point where I'm afraid to strip or snap whatever it is I'm screwing into...which would make a minor annoyance a big problem

The threads on the screw or in the brazed-on boss will give long before you bend the frame.

Good to know! Sometimes i think too much into things like that

get an old inner tube, cut it open and lay it out flat, set your cage over it like it would sit on frame, trace the shape of the cage mounting flange onto the tube to make an isolator, cut it out and remount your cage with the rubber gasket between the tube and the cage. just an idea, never tried it because my cages don't rattle.

Are you sure its not the bottle rattling in the cage and not the cage on the frame? One of my small bottles rattles the cage, but my Polar bottles are quiet.