What is the most efficient heating source for radiant floor heating?

I am replacing a twenty year old steam boiler and steam radiators to a radiant floor system. I am so confused by the number of choices to heat the water for this system. I could use a traditional boiler, a tankless hot water heater, or even a wall hung combination boiler and tankless hot water system. What is the most efficient system that will offer the lowest heating costs? I can use either oil or propane. Natural gas is not available in my area. My house is a 1100 sqft cape. Thanks for the help!

View this post on my blog: http://madeinhome.info/what-is-the-most-efficient-heating-source-for-radiant-floor-heating-2