What engineering branch is best for someone that likes to solve a lot of math problems?

When it comes to mathematical problems, you won't be disappointed if you become an engineer. Engineering is all about using math and sciences to resolve problems.

I don't think you should wait for people to tell you about various engineering careers. Check them on Wikipedia! Do your own research to avoid bias. Also you need to check computer science and information systems.

You should bear in mind that engineering, regardless of the field, is applied science. Math is one of the tools (perhaps the main one) that we use to solve problems and create solutions.
All fields of engineering use math, but how much depends on what you need to accomplish.
Think of what interests you: buildings, bridges, cars, planes, electronic devices, plastics, chemical processes, biological or industrial systems, computers, etc, and that will help you focus in a field of engineering.
You can also pursue applied math and get into codes, cyber security or "heavy duty" analysis.
Good luck.

I agree that the answers above are good responses. If math is your string suit and engineering is your interest, you can consider getting an advanced degree in engineering and going into research, perhaps at a university.

Pete Sturtevant, P.E.

The two answers above are very good. All engineering require math from simple algebra to differential equations and calculus. Engineers that work in development areas, verses established processes/technologies, tend to use higher levels of math. Good luck.