Double Dash by far is my favorite one. There's so much great about it.
When you got hit by any shell, banana, car, ramming into another kart, zooming through another kart with a mushroom, you really felt the weight of it. There's was this feeling of getting hit that felt so much better than getting hit in any other cart game. The drifting felt the best there for me as well. The battle modes were amazing and the two item system was great. The fact that some of MK8Deluxe's best improvements were adopting the double item and the battle modes from Double Dash is just telling. (Either coin runner is new or I think from MKDS)
Most importantly, it was the partner system. Making mistakes, sabotaging each other, eventually getting that synergy, making up for each others flaws to become the best kart racer and battler was so incredibly fun.
Making a Double Dash 2 with similar physics and the quality of life improvements from the new games would be great.
DD > DS >= MK8 > MK64 >= Super Circuit > Wii
I didn't get to play the original or MK7
