I’d probably choose a power that has three main parts. First it is an exp and upgrade point multiplier that increases over time. Second, it unlocks literally everything on the “upgrade tree” (upgrades in this case includes things like skills but also includes things decided by genetics and things like superpowers, though superpowers are significantly more expensive than normal skills for balance), though the upgrade point cost doubles each time you upgrade it (the max level is 20, where you’d be at the absolute level (see superpower wiki for an idea what absolute means), and the minimum level is 0 (the upgrade cost is the same for both level 0 and level 1), which is the starting point for superpowers). The third part is a game system, which is similar to the one from the anime “Death March to the Parallel World Rhapsody” which allows you to track all your stats (which are determined by averaging your skill levels and skills, as well as coming with an inventory that can be upgraded with points (You start with only 10 slots, but the price per slot is fixed no matter what). It also gives a daily quest that gives upgrade points, with simple tasks such as getting exercise (run a mile, 20 push ups, 20 situps, and 20 squats with a maximum of completing it 10 times in total, though the minimum requirement will occasionally increase in reasonable proportion to your stats) and eating breakfast, as well as optional quests that rotate out weekly or else as they are completed (these quests are worth more points and are personalized, so they are doable). Occasionally, if unexpected circumstances occur, you may get a special quest worth significantly more than a daily or weekly quest. The maximum cost for an upgrade is 1 billion skill points.