I play both a couple of times a year, very different courses IMO, i would say spey Valley is up there with the as one of the best courses Dave Thomas designed, but it is long with some hard holes.
BOG is a great course, much shorter, with only a couple of holes you need a driver and thats off the back tee. i would say more enjoyable maybe.
only problem with that time of year, you may get decent weather ( or snow), but due to where they are grass won't really have started growing then, so will both be a bit scruffy.
BOG for me , though i do like Spey valley
