Hotels chains have nothing to do with how well internet works at individual hotels. No hotel group (Hilton, Marriott, Hyatt, etc) micromanages their hotels (which are mostly franchises). Internet speed will be based on the provider and the infrastructure at each hotel.

You won't get a lot of eyes on this post. That fact means it's unlikely that you'll get a response to this question.

As someone who used to work in hotels, I think your best bet is to find a hotel that meets any other requirements (price, location) and call. Ask to speak to someone in the "onsite Reservations Office" or the Front Desk. A staff member in those areas should be able to give you the approximate speed of the guest internet. If they can't or don't offer to find the answer, move on to the next hotel.

Doing that will take time. Alternately, you can ask your Travel Department (if your company has one) to handle this for you. Or if you have access to a professional concierge service, ask them to help.