I think tailwheel teaches you to use the rudder more and highlights the importance of staying on the centerline and straight. Nosewheel planes tend to forgive bad habits. I think the Champ is a good trainer. I think the Luscombe is trickier to land, so if you learn in one you'll be able to fly most of the small tailwheel planes. I spent 300 hours in a Decathlon, then jumped in a Luscombe and was amazed at how much more responsive it was, especially on rudder.
Now the other part of a Champ, or similar low-powered tailwheel plane, is that it will teach you that horsepower won't save you if you don't have it. It teaches you when you're headed toward trees and looking like you're not going to clear them, you need to keep the nose down and build speed. In my Luscombe crash, I had a Cirrus pilot in the next seat who decided to pull back on the stick to "help" me over the trees. He used up any energy I had. He admitted it, and said he panicked.
I believe the average Champ is around 700lbs with 1200 gross, so with 10 gallons of fuel, you and a 200lb guy would be legal, but you won't feel like you're strapped to a rocket!