people people people
the best part of pokertracker is not the HUD! yes, a well setup HUD can be useful, but that's second to the leak finder and reports you can run.
the best part is running reports and filters on your OWN game for improvement! stop worrying about the other players stats and improve your own stats. this is the best way to understand the game, improve and move up.
who is the one player that is at every table you sit at? YOU!
some sites might not allow a HUD, but they still offer hand histories. these can be used to study your game.
i get a laugh out of people who dismiss data tracking software. sometimes the excuses sound like such nonsense lol. people, in general, are lazy and good at finding excuses to avoid putting in the work. you either want to improve or you don't. poker is either a passion or a past-time.
PS. my favourite stat is the rfi by position preflop and cbet/fold to cbet by street postflop.