Yep, personal choice. It depends on car size, running costs and capabilities and what you feel comfortable towing and backing. How many in family and age/size of kids? In the end it also gets down to what you can afford. When we went looking it was for a swan camper, because that's what I felt comfortable with buying however when I saw a 16 expanda, we stretched to one of those and I'm glad we did. Our 3 kids 10,12,14 are quite tall for their ages so we recently sold our 16 and bought an second hand 18 (caravan) of the same age. We just needed more space and we thought a toilet shower would be nice for the second van. For us we bought a van without bunks but with the separate shower and toilet. Our kids didn't really use the bunks in the last van which is weird because the boys sleep in bunks at home anyway, so we looked for a floor plan that suited us.
For me a poptop is lighter and cheaper to tow, our 16 had one larger bed than our 18 (true) so that's something I learnt. Our 16 was heaps of fun for the family. Easier to get on site. Noisier in a windy storm.
For me our 18 caravan is heavy and more expensive to tow but tows a bit better than the 16. It has more cupboard space and less cluttered when we are away.
I have a friend who recently sold his full van (not Jayco) and has ordered a poptop because he felt the caravan was too expensive to tow, hard to get on site and was difficult to get in his garage.