The aluminum top will look better far longer. Unless you bend it - then the fiberglass top is far easier to repair.

I would question whether insulating the top will actually do any good for anything, unless you are planning on heating the interior.

I've had the insulated AL top trailer for 12 years and agree with the above comments. I believe the insulation reduces sweating inside the trailer. I heat the trailer during the winter months with a chicken incubator (available at any farm hardware store). Incandescent light bulbs have been known to cause fires and this is a much safer alternative.
Al tops are a bit lighter. Reducing hail damage will probably favor fiberglass. Reducing annual maintenance will strongly favor AL tops. Aesthetics, IMO, favor the fiberglass top. Both are top quality products from Spindelberger.