When I moved my shop into the basement, I had the same set of debates about mill placement.
in the end, I opted for putting the mill in the open
I caught this exchange between my PM mill and my old POS lathe the day before I picked up my PM1340GT...
Not a week goes by that I am not grateful I put the mill out in the open rather than against the wall or in a corner. It was a really good choice even though it limits room in the shop. Being able to get at all sides of a mill is really a good idea, especially if you plan to do fussy stuff in hard to view areas.
Another mistake I almost made was putting both machines on the same breaker. At the time, I didn't think I would be running both the mill and lathe simultaneously. Turns out I actually do this a lot.