I originally used a clone of Align on my RF-45 mill. No issues. I ended up getting Align brand on the new mill because the package price was right, parts available & warranty. The only difference I can see is the Align will traverse slower. There is something different about the clones in this regard, not sure if its electrical or mechanical but others have observed. Doesnt make a difference on a knee direction but maybe on a primary milling direction. If this isn't an issue go with cheaper.
I have heard that the clones can vary - what you get at Shars vs clone-X vs clone-Y may have subtle differences so no guarantee you can get parts down the road. fact of life with any of this stuff.