Reasons why I prefer the MacBook (Pro)/OS X;
Desktop clutter: I have 10-15 programs open sometimes and switching from one to another with alt-tab or windows-tab isn't always making me find the right one fast. On Mac OS I use different spaces to group several apps and that makes life so much easier... Swiping with four fingers to switch back and forth is superfast.
Trackpad: Dunno about your X1E, but mines trackpad is so much smaller and utterly useless compared to the MacBook.
Spotlight: cmd+spacebar is so much faster and cleaner to find stuff. On Windows the big square that pops up from the taskbar is no match.
Preview: hitting the spacebar to quickly preview a document before opening it is such a timesaver sometimes...
If some of these features exist in Windows 10, please enlighten me, cause that would make my life much easier