Strictly as a personal opinion, I like the Leo 2 better than the M1.
Again, personally, I am more comfortable in the Leo. Perhaps its because the C2 and the Leo2 share the same gunner's FCS (the commander independent system, is of course, completely new...), or perhaps it's just German engineering, but I find the ergonomics better (in all positions, with the possible exception of the driver) in the Leo than the Abrams.
Now, trying to put personal feelings aside, and looking at matters as objectively as I can....both tanks are relatively easy to train on, both being designed with a conscript army in mind. Both tanks have an excellent FCS, although other sources give a very slight edge to the Leo's FCS. The turbine is a logistical nightmare, requiring very expensive rebuilds more often than the MTU diesel, plus it devours much more fuel. The logistical spare parts tail, as was previously pointed out, is much shorter (and possibly much cheaper) with the M1.
The Americans successfully trialled a M1A1 with the Leo's diesel engine. That it was not part of the M1's A2 upgrade was simply because the diesel is not American.
Perhaps the best trade off for Canada, assuming a MBT buy, would be buying surplus M1A1, rebuilt with the MTU power pack?