my friends keep arguing over who's the better rcF tuner. Loi or reflash and i cant seem to get a proper answer online. who do you guys think is a " better " tuner and why?

Who's the "best" tuner will be debated until eternity. Try messaging both yourself and then just go with who is most informative and responsive. Dyno sheets and track times are better documentation than Instagram hype videos of roll racing.