I think it was chosen because the addition of two elements in GF(2^8) with their binary representation is a XOR. Which is a really efficient operation.
"That first one that worked (100011011) is the one used in AES"
i.e., the polynomial that was chosen for AES (x^8 + x^4 + x^3 + x + 1) is the minimal irreducible polynomial of degree 8 (minimal in the sense of the natural ordering of polynomials). I guess that could be a good reason (but I'm not sure it's _the_ reason).