Schluter heated floor system is fantastic for your electrician and your tile installer. Usually a nicer tile store carries it or has access to it.

Ditra has an "all in one" product that tile setters swear by (not swear at). It is pricey but saves a HUGE amount of labour and is a very good product. Talk with some tile setters who have worked with Ditra and the heating system by Ditra. They will help source what you need and install it as well.

We're talking about the same product. Schluter is the manufacturer.

Depends on a lot of factors. Want low voltage and a 25 year warranty? Check out Floorizwarm. Looking for a rollout mat? Heatwave works wonderfully. Working on a larger area? Tuff Cable and Cozy Heat are great options.

We've worked with and installed each of these products (and others) for decades and they are all great. Share a bit more about your bathroom (size, floor covering, unique obstacles, etc) and we'd be happy to provide more detailed recommendations.