I've used every single OS mentioned in this thread so far and I'd have to say if you're still using XP you should seriously consider upgrading to at least Windows 7.
XP is WAAAAAAY to easy to hack into.
HAH why are you still running this? Maybe if your PC isn't connected to the internet at all. Windows 95 is basically where Microsoft started it's venture into the GUI of OS. This must be your souped up 486 with turbo that you play SP Quake ONLY on right?
This is essentially Windows 95 with service packs honestly.
While Win98 still had huge security holes and isn't recommended anymore for a modern day OS.
Initially i protested WinXP and vowed to stick to my Win98 guns but at a time of great despair (mandatory format) My Win98 OS install disk was lost after I moved states.
This is where (I think) most everyone should be on their production PC. If it's connected to the net and you're not a power user I suggest you use this version of Windows. This is a good example of what happens after MS gets enough time to fine tune their OS I feel.
I'm currently stuck with Windows 8 on my Laptop and the whole touchscreen enabled OS on my non-touch-screen enabled laptop really makes me ponder "Why the heck did they install a touch-aware OS on a non-touch aware laptop? Makes no sense why.
Once you find out where the Desktop is on windows 8 you gain some familiarity from Windows 7 back but get this, WINDOWS 8 HAS NO START BUTTON.
I paid $3 for a program called "StartIsBack" of something that mimics the start button of Windows 7/Vista/XP and now My Windows 8 functions more like Windows 7 which makes me happy.
Windows 7 should still be a standard on all NON-TOUCH-ENABLED-PC's.
Windows 8 seems like it's trying to count their eggs before they hatch with the amount of change Windows 8 brings over Windows 7.
Just my opinion from a person w ho's used every single MS OS starting with DOS.
If you pay attention to this type of stuff then you probably know that Linux (specifically Ubuntu linux) is making huge advancements on becoming a "regular user's OS" which I highly recommend for anyone wanting to try something fresh,new and free, also you don't have to worry about viruses like you do in MS Windows.
Vista is essentially what XP should have been.
Windows 7 is the current sweet spot and I have to say at first i didn't like the changes as a power user coming from XP, it felt like they hid a lot of the options I was use to messing with as I traversed the XP interface. Win7 still has a huge variety of settings but they're ?optimized? Honestly I prefer XP's look but Win7's functionality and security.
Even though I use windows 8 I recommend Windows 7 to all.