1917 and 1919 should be recognized A&M championships. Simply put, we were the best team in the nation those years by just about any criteria.
USC's claim to the 1939 championship is pure bull**** - a team with 2 draws is in no way better than our team that was undefeated.
BUT 1917 and 1919 are different.
1927 is not as clear cut, but we did have the same record as the top teams (no team was undefeated with no draws that year). I personally wouldn't claim it, but we do have an argument (because SWC teams were perennially underrated at the time).
1956 we have no legit claim to. Oklahoma demolished everyone that year, went undefeated (and untied) and we had a tie on our record.
1994 we also have no quarrel with, as both Nebraska and Penn State were undefeated (and untied) and we had a tie on our record. Regardless, probation made us ineligible for the championship, and I doubt they would allow us to retroactively claim it.
So basically, I would be very happy seeing A&M claim 1917, 1919, and 1939. If we claim 1927, I wouldn't disagree, but I also wouldn't lead the charge to have us do so. Other than that, we don't have a legitimate argument.