There are pros and cons with either. If you intend to just drive somewhere set up and stay there for two weeks and then come home again, get a caravan. If you like to stay somewhere two or three days and then move around in my opinion, get a motorhome. We have a Sprinter van and within five minutes we are plugged in and chairs out having a drink. We see people with caravans taking ages to get set up. Legs down. Back and forwards. Fetching water etc. I just pull up the handbrake and connect the electrics.
Converting a van is expensive, but you can
DIY camper van and save some money. Personally, I want the project, so I enjoy spending all my spare time building out the van. But if you are more interested in using it than making it, then I suggest buying something already made.