I have a Master's degree in physics from the University of Copenhagen and I have taught together with one of the leading climate scientists from that university Bo Møllesøe Vinther. He claimed that the best dataset on global average temperatures is satellite based and is the University of Alabama in Huntington dataset (UAH) which goes back to 1979.

You can find it here: https://www.nsstc.uah.edu/climate/

Direct link for monthly temperature averages: http://www.nsstc.uah.edu/data/msu/v6.0beta/tlt/uahncdc_lt_6....