Are any types objectively better than others?

[Yato]

Steel is definitely the best defensive type. Even with the Steel nerf it still resists a lot. Offensively, I'd have to say either Ground or Fighting are the best. Both are strong against four types (Rock/Steel/Fire/Poison for Ground; Normal/Rock/Steel/Ice for Fighting) and have common, powerful, and easily obtainable moves (such as Earthquake and Focus Miss Blast) that many Pokemon can learn (particularly via TM).

In terms of worst types, Ice defensively and Normal offensively. Poison is near being the worst offensively, too, but a lot of moves poison or badly poison, and the latter is definitely not fun to deal with.

 

[BadPokemon]

I feel no type is better than another- each has their own uses, strengths, and weaknesses. Grass and rock type I think are the only exceptions. Both are inferior in terms of number of weaknesses and lack of advantages. Rock is terrible defensively, but ok offensively (due to lack of ice types). Grass types struggle offensively and while having good defenses, have too many exploitable weaknesses.