>>9033735Depends what you're into really. I try to be a little strict about buying figures from shows/manga/games I actually care about because it helps me stay attached to the figure.
However, I'm big into mecha, and have a handful of gunpla from series I haven't or probably won't get around to watching. In that case the design is the main factor, and that also goes for toylines that are independent and only have a tag-line of background lore.
So really it's just something you have to gauge for yourself, what's meaningful and will leave a lasting impression in your collection. It's easy to flood your shelves with things you "should" like, but space is more limited than money, so I try to keep my collection as permanent as possible. On top that, you can always check out the series afterwards, that's always fun too.