It's sort of an own vs. rent question. You can get advice on demand from someone on clarity whenever you want, but it's not likely they will go to bat (or go to bat for free) in the same way someone with equity will.

I viciously defended equity in my first company but my partner and I were responsible for all growth. The big upside connections, etc that can a good mentor can bring (especially one with relevant industry experience and contacts) are not something you'll be able to get on an hourly rate.

It kind of backs in to the old 100% of a grape or 50% of a watermelon question that comes up when raising VC. Except in this instance it's 100% of a grape vs 99%+ of a watermelon because advisory roles usually don't take a ton of equity.