To me it depends on where the fan is being installed IMHO. In the front lounge, any will do. In the bedroom I would want insulated. If you only have one vent because your trailer is small, then it is hobsons choice
I have had or have had all three. The tinted cover is nice, it acts like a skylight. The translucent is nice too, no glare, but light comes in and The UV is not an issue. The insulated domes are 100% light blocking.
I currently have 2 insulated and one translucent installed in my MH. The translucent one is in the galley section, where there is a lack of light as it is.