Wet coast?
...I'm not sure Norm's airplane in Victoria even counts as actually being exposed to 'the elements' !
ok, he DOES have to contend with the sea air, sea gulls, sea shells by the sea shore etc.
I think the locale will determine your preference to some degree; and what i mean by that is.....here in the Okanagan/southern BC, there is plenty of hi, low temps, sun, rain etc.
...but what really seems to effect the aircraft is dust! There's a nearby gravel pit, upwind, and highway, and the grime and cr@p that accumulate the day after you wash your plane can darn near render it u/s.
I use the heavy Bruce's canopy cover at home, and the light fly cover as a sunshade when away ( and to keep prying eyes out).
My personal opinion is that covers, if not perfectly secure, will chafe, and that having a breeze blow thru the structure, keeping it dry, is a good thing......but lots of guys use full covers, and love that you can just go out, pull them off, and fly, with little or no cleaning of dirt or frost.
Then there's critters. Birds, mice, marmots, can all get into your plane, causing varying degrees of pain. Covers may limit access points.
so there's a long winded " it depends"