I like the clarity and simplicity of the first set, although I am sort of reluctant to say that. Will it help if you get 3 replies, one for each board?
What do I really think is the best set for study? Any one with a clear and straightforward design. I had a friend with one of those fantasy Lord of the Rings sets or something. Too much time gets spent trying to remember which piece is which.

So, Here are 3 different sets. One wood (9.4" but smallest squares because of the large borders), the other two plastic (9.8" black and 9.4" brown).
All are roughly same size, 9.4-9.8", with 1.75-2" tall King.
All are within $10 of each other.
Interested to see what folks like the most (purely subjective I know, just getting other opinions.)