Ugh. I'm still playing Balatro
I can't remember the last time I've lost a game on the first two difficulties, so at least I have that going for me. I can always find a way, regardless of RNG, to win those.
The thing is, a pair, two pair, and three of a kind all have a pair in them, so from my perspective it's a waste of resources to improve all three, and I just focus on "a pair". You could say the same thing for High Card versus everything else, and that would be valid, as well, but a Pair is very nearly as easy to make as High Card and getting to count an extra card makes a huge difference (if you don't have Splash, which I usually try to have)
Here's EXACTLY how I handle planet cards. If I open a pack and Pair is available, I buy it. Doesn't matter what else is available. I always buy Pair if it is there.
If Pair isn't there, I buy Straight or Flush. Why would I improve Two Pair or 3 of a Kind when I already have that scenario (multiple copies of cards with the same rank) covered with Pair? Focusing on only one of those three pays big benefits long term. These two, Straight or Flush, offer the chance at a significantly better payday and help cover situations where you don't have a pair. But if none of these three 3 are available, I'll pick High Card, although I can't remember the last time I actually played High Card. After that I don't care and would just pick something random, but generally I would take Straight Flush if available.
If I am given a free planet card for something other than Pair, Straight, Flush or High Card, I sell it.