I have only flown one other airplane that handled as well as the RV3 and then some, and I own it. Overall performance, hard to beat the 3.
However, you would be surprised how well a legacy RV4 or RV6 handle when they are not plumped up with big motors, heavy CS props, fancy interiors, etc....but most of us made those choices for other reasons than pure handling.
If you have ever flown a sub 1000# 4 or 6, they are not that far off from the feel you get in a 3. The 4 suffers from the compromise of accommodating a back seat even when solo and the 6 in balance to a degree in solo due to seating position.
The 3 still wins in overall handling enjoyment but we start splitting hairs between all the models, especially the light legacy 4's and 6's.
The lack of utility of the 3's makes them like the sports car world. Nice to have but not very practical when most consider what they want in an airplane and the resources they have to put to a "hobby", in both time and money.
I wish I had a 3, and Honda Jet, and a SuperCub, and..??.., oh, and limitless time, a mechanic on call, a fuel farm, ..... you get the point. If you only can support one airplane, it probably isn't going to be the 3 unless you want it for "social" aspects