That's one of the reasons Arc Nova is such a replayable and enjoyable game.
The decision is based on a number of other starting factors, Including which cards you choose to start with, the starting order of your Action cards, the starting display lineup, your hidden goals, starting map, how fast you think the "race" will be, and the number of players.
If there are a lot of players I wouldn't choose Association. You're not as likely to get the Partner Zoos/Universities you want, make the Donations you want early on when they're cheap, but number of players can't stop you from buying the +2 Reputation Association action. But what you choose might affect what other players choose.
A high number of players means you're less likely to get the card you want from the display, even if you upgrade the card action.
If you start small animals and/or the Small Animals Conservation Project, you might not want to upgrade the Animal Action card. Contrawise, if you start with an animal that needs Animal L2, and you keep it to build up to that, and start with the Large Animals Conservation Project, go for Animal L2.
Same with the Sponsor. Building and Card action cards. See above about Upgrading the Card action card
Your choice should depend on a number of factors. IMO, never lock yourself into one choice of what not to upgrade. Look at the entire starting setup, keep your options open, and be flexible. The same order might not be "right" for every game you play.
Some of it is personal style. I have bad luck drawing Sponsor cards, and prefer discarding the action for money, and getting any necessary money elsewhere or waiting. Also, I find the Sponsor action lack the least limiting. So not upgrading the Sponsor Action is my go-to. Your mileage and others may vary.
The one thing I found is that the one Action you didn't upgrade is the one you wish you had
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Overall, they are all good choices. But they are... circumstantial.