As with most things in NBA 2K24, the Affiliation you choose will largely depend upon your build. If you select RISE, then you're probably going to want decent perimeter shooting attributes to start with, because you're going to need to be able to drain plenty of buckets in order to unlock the Heat Check gameplay boost. The Finishing boost will benefit builds with strong dunking and layup abilities, and also the Playmaking boost can come in handy if you're a team player.
However, overall we'd recommend ELITE as the stronger of the two options. If you already have good Defensive attributes then they're going to get a significant boost from the Affiliation, and it's worth noting that making a good play on defence is going to buff your player on offence and vice versa with the Two-Way Tenacity perk. Factor in the Shooting attribute boosts, and it's inarguably the better of the two options — but it does depend very much on your build and personal playstyle.
Do keep in mind that whichever Affiliation you ultimately decide to choose, you'll need to complete the Affilitation's respective quest in order to become a fully-fledged member. You can find these quests in your Quest log after speaking with both Chris Manning and ShakeDown near the beach.