Hm. OP, Naruto, Bleach got name Big 3, because they were for long periond three best sellers mangas.
1. OP will not end soon, probably manga you mention will end before OP's end, so OP will always be part of Big 3.
2. Bleach probably will not end soon, either.
3. Naruto will end soon, so it leave only one place.
If I remember correctly Toriko sales are not really good it's even weaker than current Bleach's, so it's out. Tho, I'm not sure about HxH and Magi.
1. OP will not end soon, probably manga you mention will end before OP's end, so OP will always be part of Big 3.
2. Bleach probably will not end soon, either.
3. Naruto will end soon, so it leave only one place.
If I remember correctly Toriko sales are not really good it's even weaker than current Bleach's, so it's out. Tho, I'm not sure about HxH and Magi.