There is a trade off between ride quality and puncture resistance. Schwalbe Marathon Plus are mentioned more than any other tire because they arguably have the most puncture resistant tire on the market. They are indeed hard but with a loaded touring bike it isn't that big of a deal since you aren't doing 25mph on the flats. Armadillo tires might be next in line. Many consider them to be a worse ride than Marathon Plus but not quite as puncture resistant. Conti Hardshell are not quite as tough but have a much better feel. If you're looking for something for good touring but puncture resistance is not the end-all thing then Hardshell are worth trying. If I had to make one recommendation it would be Marathon Plus and you'll find them mentioned over and over. My wife was braced for a harsh ride due to my comments but when we put them on our Salsa Fargo with a loaded setup she was quite pleased, even more so than I.