The RV's all vary in style and capability in ''my opinion'':-
RV4 small and aerobatic and fun but limited person and baggage space.
RV8 bigger and aerobatic and the ultimate macho fighter version.
Both these are Tandem seating, where the passenger is in second class.
RV6 lovely tourer with good baggage space.
RV7 updated version with bigger fin and wingtips.
The 6 has AUW 726KG and the 7 AUW 820KG, thus 7 better two up for aero's. Some landing and parking fees change at 750KG !!
RV9 similar to 7 but bigger wing and tailplane, so better out of strips.
Then of course the big debate tailwheel or nosewheel. Pro's and con's, the nose wheel is prone to digging in and nosing over, but better ground visibility. Tail wheel not good on rough grass due to springy legs attached to engine frame. I think nosewheel is an ugly afterthought for the America's.
New RV14, probably now the best of the two seater side by side.
Effectively a larger version of a cross between a 7 and 9
RV10 Ultimate 4 seater homebuilt, but thirsty IO-540 engine.
RV12 small two seater, cheaper to build, Rotax engine !
So, they all have their attributes and differing performances.