If you insist upon using the valence bond hybridization model, it would be sp3.

However, this hybridization model is rather dated. It was a nice thing when there were no computers yet to give us more accurate descriptions of the electronic structure. The fact that the free electron pairs of the O interact with the aromatic system will be automatically accounted for in modern quantum chemical calculations while in valence bond it will have to be reintroduced manually.

As a starting point, you can use an MO diagram of water and the depiction of the orbitals localized on oxygen therein. For phenol, you can expect something similar with a few up- and downshifts.

If you're interested in scientists throwing insults at each other about the topic, dig into

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