I like cloak v cloak the most. its pretty fun to micro glaives against glaives. the factory has all counters to itself, so the matchup feels very fair and balanced (which is somewhat ironic to say in a mirror matchup)
rover v rover is also pretty fun, but it can be pretty difficult. if you msmicro your scorchers, your opponents scorchers could easily take a strong position and now you're helpless because you cant chase scorchers with scorchers. a random raid of scorchers could beeline to your lab and instantly end the game. if you tech too late, your opponent might snowball a fanser or ravager advantage. if you tech too early, you might not be able to deal with scorchers. its all very difficult, but it doesn't feel painful because its so dynamic.
spider v spider is kinda unpopular, but I don't mind it. flea v flea battles in the opening can be fun, and I like using flea maphacks. I feel super op when I can kill a commander or an army for free because I used flea haphackz to see when they were out of position. I also feel like @Godde when I play (and win) spider v spider, probably from watching him and
izirayd spam the matchup :P.
I don't play enough hover v hover, amph v amph, or jump v jump, shield v shield, or gs v gs to have any strong opinions, but I still have some first impressions . I think that jump v jump can feel weird since it seems like its a race to modspam? hover v hover feels like a dagger race -> mace race, but I'm not sure. shield v shield seems super weird, because I'm not sure if shieldballs can actually kill shieldballs.
I think I like tank v tank the least. the units can't really kill eachother, and this especially becomes more true as you tech up to tankier and tankier units. It's a ton of wet noodle fights with tanky units. it doesn't feel like I can interact with or counter my opponent. the games just feel bad.
I think that's all of them! so for me it would go CvC > RvR > SpvSp > HvH > JvJ > GSvGS > SHvSH > TvT