Well if you ask 10 people you'd probably get 12 different opinions, but if you're talking best plant food like "Best in the World" I'd have to cast my vote for Advanced Nutrients.
Some are better in soil, some in hydro, but in my experience at least AN will outgrow anything else consistently in any setting. I haven't tried everything or every setting, but I feel safe saying that Advanced nutes would win any battle it was put in. So for that I'd say it's the world's best overall plant food currently out there.
In fact, the company founder just recently put up a million bucks in a challenge to the competition. He said he'd pay a million dollars to any competitor that could personally outgrow him with him using his stuff and them using anything they want to use except Advanced Nutrients. So it's not just Advanced Nutrients against one competitor, he's challenging any competitor using any/all of the plant foods in the world - best of the rest if they like.