I personally found that Lima Fit AAR was not too difficult unless the tanker was a KC135 with a BDA. Yes you had to use burner, but the burner light-up was so smooth it was not difficult.
Mike Fit, 8 missiles, TRD and Phimat could be fairly challenging. Also some of the Alarm Fits had a high DI and so were difficult.
Heavy weight C130 AAR was also OK but one had to be careful coming off the tanker full. I personally advised crews to keep the SPILS On despite what the RtoS said.