never take blurry & hazy UFO photos/videos again

Of course the sensor is important but as long as you try to capture light through a grotty piece of plastic 5mm across which has been rattling about amongst the fluff and general crud in your pocket for a few weeks then you are on a hiding to nothing.

If you don't collect the light in a decent manner to start with it will make not the slightest difference how many mega pixels you have you'll just get more pixels of poorly defined fuzz than one with a lower grade sensor.

If you really want to take worthwhile pictures buy yourself a camera with a moderately good sensor and the best optic you can lay your hands on.

Oh, and a tripod, please.

It's not the shutter speed alone, that's where the iso sensitivity comes along. You have to have a high enough iso so you will have short enough shutter speed to eliminate prefertably all movement in the picture. IS system of course helps with that but if the UFO itself is moving then the it's best to have a fast shutter speed.
As someone mentioned canon 5D and now also nikon D3 have physically big pixels on the sensor. The megapixel count is smaller, but the images come out crisp and with very little noise even with higher iso's.
In 'UFO photography' it would be important to have sensitivity so you can get those pesky greys to pose properly even in low light situations