Ricta 99a (everything but naturals which are 101, and the one pro wheel at 98...talk about splitting hairs there) - grippy and fast. Much faster than spits (any shape, any duro).
F4s feel great, like mentioned in another post, they feel like old school urethane, which is awesome but I find them slower (in parks) than say an STF or Ricta and just wiiiiiiiiiiiiiiiiiiiiide. I've tried just about all shapes and duro combos except full conical 99a, which I assume to be akin to skating on apples, slow and mushy. The duros seem much too soft.
OJ insane-a-thane, shitty name/marketing be damned, are my new favorite wheel - just picked up a set of 101a hardlines (park shape, i.e. spit conical/SPF P5 shape/my fav shape). Been skating the ez-edge wheel, which is a traditional 'street' shape, e.g., spit classics, bones V1 - Fast, grippy, slide great and chirp nicely. I like them better than my 99a rictas as they are a lilttle less grippy. They feel great on both rough/smooth street and parks (much like STFs are the same way); they feel right in the middle of ricta and spits to me.
The insane-a-thane is a totally different formula than the slow ass regular OJ thane; night and day difference. I've seen more and more insane a thanes at my park which is usually indy/ace/bones/spit.
SPFs are fast and hard but too slick for me since I tend to go fast and slide out. Same with STFs
Autobahn - too grippy for me, tho the 100a formula is quite nice on a thin wheel
The comment about colored than is on point, any colored wheel I've ever skated has always felt different; in the case of colored STFs, they felt better.
They all flat spot, just figure out what you need: do you slide all your tricks that extra 45? Rerverts? Blunt slides? ledge shit? Get a slidey wheel...just drops and rails? Find a shape that locks in and feels good.