An excellent question.
I just bought the Incra, 1000 for $100 delivered.
Most things I have read suggest that the Osbourne is a better miter gauge. But it costs more ... anything from $20 to $60 more, and I wondered if it was really that much better.
The Incra appears to be well made, and the micro-adjustment is as much accuracy as a woodworker could want ....
I guess I would be very happy to use either, but budget dictates