Went from a fifth wheel to an Aria 3601 in 2017 when they first came out:
1. Less driving stress. Actually a pleasure to drive. You are not being pushed by something that weighs 2 to 3 times your vehicle weight.
2. We had a short 31 ft. HT 5th wheel. With vehicle connected we were pushing 46ft. total length. So, the 3601 if 10 ft. shorter and does not have a middle "joint" to deal with. Parking is a breeze.
3. We looked at all makes and models (still do actually) and the Aria had the best layout and features included in the MSRP with wading through a list of options.
4. Thor: We have been blessed with few to no issues with our unit. When I have called Thor with questions I have a 99.7% positive satisfaction rate with the responses and help provided.
5. Just the two of us plus dog, but 8 grandkids. The unit accommodates us great but easily supports more without having to think about a bunkhouse layout.