If you ahve any knowledge about the internal structure of a Operativssytem, then you wouldn't say that Windows 7 is best in anything at all.
OpenBSD is best at security (used by Pentagon etc), Solaris is best at modularity and speed, FreeBSD got superior network (a reason it's one of the favorite choices on firewalls), Linux is overall best at new technology and driver support, yes, even better then Windows... And got a supperior look.
Mac is just plain diffrent. It isn't supperior in any field, but it looks nice, got good software support, and overall good performance and stability.
MenuetOS is supperior when it comes to size, overall good performance too.
Windows well, because of illigal marketing they have managed to get the dominant share of the destkop market (Atleast 80%) and a significant piece of the server market (10-15%), because of the amount of Desktop users, most software is developed towarns this platform. Altho most serious buisnesses looks at Mac and Linux do to WAY better stability and performance.