hard question because i have an insatiable sweet tooth that has not gone away in adulthood lol. i remember struggling hard with the chocolate fest because i was like BUT THEY'RE ALL GOOD!!
it's hard to pick a flavor that could apply to a variety of candies but i guess if i had to pick a favorite candy it'd be maple candy. i had maple cotton candy at a fair too once, so if more candies came in maple i'd probably eat those up (literally). when i was a kid i'd gotten the impression that maple candy was a rare delicacy though, only available at small kitschy shops far from home (i'd eventually realize that the store we'd been going to is a pretty short drive from home, i just had no sense of time), and i think that still colors how i feel about it... but also it's so good either way
but tbh my tastes in candy rely a lot more on what the candy is than the flavor. like, i can't really think of a flavor of rock candy or cotton candy i wouldn't want, because i love all the stuff my parents used to insist was Just Sugar (as if that'd dissuade the kid who occasionally got caught eating straight sugar)
favorite chocolate though depends a LOT on my mood. the biggest thing that's changed about my tastes in sweets between when i was a kid and now is that now i like dark chocolate as well as milk and white. big fan of (any) chocolate and peanut butter though