If I had to think really , really hard.... and that's might hurt... about the absolute one piece of advice I'd give a guy who wanted an ultra fun cub. This would be it;
Do not be 'the man in the middle'!
I mean don't compromise! If you want an absolute rip snorting load hauling brute, 160hp and stock wings ain't gonna cut it. Heck 180 hp is really just the minimum ante here... Barnstormers new ride is a really great example of cubs in this category, and no way no how is 160 piper winged cub gonna even come close to comparing. An experimental Carbon done right will do it, but it'll cost...
On the other end of the spectrum is the sweet flyers. (sorry Barn... I really mean no offense by this, but slatted planes do not fit my definition of a sweet flying wing, they do AMAZING things for sure! but they have a very unnatural flight charecteristic to me

) The reason you hear the old salts talking about how sweet a 90 hp cub flies isn't magic... hell it's the exact same fuselage, wings and tail as it's big brothers..(well ok there are 3 extra ribs, and two extra tubes...) externally, and dimensionally identical!
The reason these light cubs are such an absolute joy to fly is because they are LIGHT and CG'd appropriately.
Hang a set of 35's on a 150hp cub, and it's going to be a pig. Do up a set of Dakota wings with extended leading edges and dual lights, extra wires for strobes, then load up the panel with a big CC square job, stack in a HD windshield, HD 3" gear 6 bolt clevlands, heavy CC seats, a belly pod, X braced tail and top deck, under baggage x for the third set etc, etc, etc and you are going to have a turd...
The other side of that coin is when you try and build a snorter, and skimp... You go into those knowing you're going to weight 1200#'s or more... Plan accordingly (long wings, big engine, and big prop) and you'll more than compensate for the extra weight. Try and skimp and you'll be disappointed with a brute of an engine that is in a body that flies like a brick. Every top cub I've flown pretty much fits that bill... pulls stumps, but flies like a pig...
There are only two kind of folks who don't notice the extra weight or screwed CG in a cub... Those that are so good they can make a pig shine, and those who are so inexperienced they really haven't learn the nuances. BTW, if that last statement sounds a bit prima donna, you're reading too much into it, we've all been at ground zero, and we all have plenty to learn yet, and me more than most
Take care, Rob
Wait! Wait, Wait... that's all almost true... the best advice? Take a level to the pre buy and measure the cub up. If it doesn't measure really good, walk. You can do a whole new engine for what you'll spend cutting loose the top deck and sliding it back if the AOI is not right, and many aren't. Few are OK, and even fewer are wrong in the direction that makes them better than stock...