>>1788869
The wiki has general guidelines on what's best to use, but 90% of the time, it will be the newest releases hogging the arena meta and many other places because the power creep in this game is just like that, newer cookies just get better from having many buffs, giving a lot of strong debuffs and doing more than previous cookies, but yes, the higher rarity and marginally the higher ascension you have will be better, up to the point that Shadow Milk Cookie could solo an entire team of the most recently released epics when he came out for example.
https://cookierunkingdom.fandom.com/wiki/Cookies_Tier_List