With the 4 cyl, you are going to be looking at a popup. That's not a bad thing. We had one that we loved for 9 years, and took it all over the place and had a great time in it.
The main reason we changed to a TT were my teenagers did not like sharing a bed anymore, and my mother in law is now a widow, and we take her with us regularly. We just needed to go to a bunkhouse floorplan. If it wasn't for that, we would have probably stayed in the popup.
Also if you can find a used popup in good condition, they hold their value extremely well. We bought ours when it was 3 years old for $6k, and used it for 9 years, and sold it for $5k. It was garaged kept for all but about a year of that time, and was in great shape.
Good luck in your search, and don't write off a popup, they are great little campers.