In Balatro there's no such thing as Joker upgrades or "levels" and Im sure its not a concept Local-Thunk would explore, not even by chance.
However, there are only 2 pairs of jokers in which one is STRICTLY better than the other.
And by STRICTLY I mean that it is better 100% of the time, and there's not an argument that can state the oposite, for example : We all know that Acrobat is worse than Card Sharp ~95% of the time, BUT ITS NOT A 100% , so there's a few times where Acrobat is better than Card Sharp, and it may save your run.
So having said this, here are the only 2 pairs in which one joker is strictly better than the other.
Onyx Agate (+7 mult per Club played) > Gluttonous Joker (+3 mult per Club played)
Not much to comment about this, its pretty obvious
Chicot (Dissables the effect if every boss Blind) > Luchador (Dissables the effect of the boss blind if this Joker is sold)
While Chicot Dissables every single Boss Blind, Luchador can only dissable the one you choose by selling it
COMMON MISCONCEPTIONS
Blueprint (Copies the ability of the right joker) (not always > )Brainstorm (Copies the ability of the leftmost joker)
Obviously both jokers are incredible ,but Brainstorm lacks the ability to copy ×Mult jokers with the optimal positioning, while Blueprint is able to do this. BUT Blueprint is restricted as it cant copy the leftmost joker, and this seems pretty stupid as jokers can be moved , but if you have 4 of polychrome jokers or scalable ×mult jokers that havent reached ×2 mult, and for example you have a +80 mult Spare Trousers, It is better Brainstorm as it can copy the mult joker, giving the effect of an 2× mult joker, while keeping an optimal positioning, a thing Blueprint cant do.
Triboulet not always> Photograph
Simple, with pareidolia Photograph always activates while Triboulet doesn't, as it requires Kings-Queens specific ranks, and also if you are building for a 5 of a kind jacks run, Triboulet is worse than Photograph
Thx
for the forgetful ones, onyx is a build, glut is an addition to a build. Chicot is a background/passive joker, luchador requires more thought and strategy from the player, making it more fun. Remember the game's goal is to make money and, more fun>makes people play it more>makes more exposure>makes more people look into it>makes more money, well unless BLT just wants us to have fun, where that makes it more simple, more fun>more fun.