Replying to Boot Questions (I went to a Fitter)

Hey guys, So I recently went to a boot fitter to get sized for boots since it is a necessity in most cases and I've learned something new about myself. My feet are different in width and length by a few mm.

The difference in sole width is 103-104 and 106 for left and right respectively
The difference in Length is the same (3-4 mm difference)

Knowing this information, if I am between sizes lets say between a 26.5 and 27 should I go to the larger size (27) for a little more room, or do I go to the size smaller (26.5) for a more "snug" fit. I know the boot is extremely important (if not the most important) but I was recommended the bigger size since since I could just buckle the boot tighter when needed. Any thoughts on which size, also boot recommendations would be highly appreciated.