what i wanted to say me going on tangents i never found filler to be a problem in one piece mainly because of the premise and theme of the show. it's a comedy with occasional serious moments that are well paced, and it's a flexible show, and unlike naruto or bleach, filler never feels like something out of place. characters and plot lines are always consistent unlike other shounen. it still suffers from shounen recap syndrome though, which one the reasons i'm not watching it anymore. the 'best' starter anime is always going to be different for everyone. but if you're going for something with general appeal, a well-paced, balanced comedy with an uncomplicated or episodic plot is usually the best. it's also best to introduce someone with an anime that has a good amount of the typical anime tropes while still being good show on its own with a wide audience appeal, so pandering ecchi shows usually aren't good starters. one piece isn't the epitome of this, something like say trigun, bepop, and champloo are good examples, too, possibly better, but they've been already mentioned. they're not full comedies, they're balanced comedies. now, if you're trying to convince someone that anime isn't just ecchi or trying to convince a non-anime watcher out of pre-conceived notions about anime, that's entirely different. it would best to introduce them to anime that breaks those tropes and has a more serious atmoshpere, and considering they're probably not asian, has western appeal. i'm reluctant to say fate/zero, because that's setting their standards a bit too high, but for older audiences with not much time on their hands in the first place it's probably okay, death note for people in their late teens, and fma for early teens. when you said starter anime, i was thinking of a little kid's first anime, so i thought long form shounen and it was a toss up between one piece and dbz, but since i think one piece has better pacing it won.