Mac isn't better than Windows, and Windows isn't better than Mac. Both equally have their good points and bad points. I've owned several iMacs and Mac Book Pro's and the quality of the hardware is excellent and far exceeds any laptop/desktop quality. Although the downsides are the specifications - some PC's have double the specification of an iMac and is half the price. The hardware in iMac is difficult to upgrade and they don't make it easy to remove the cover to gain access to the components.
The good thing about any Mac is you're able to dual boot Windows on it, so you won't have to keep your PC for using those Windows-only applications, unless you want to.
OSX is extremely reliable and fast. I've gone months without the need for a reboot and has only ever crashed once in the years I've used it. If you've never used a Mac before, it's quite a jump moving from Windows to OSX and it does take some time getting used to it. Microsoft has it's own Mac version of messenger, as mentioned in a previous post.. and also has Office for Mac.
If you know someone who has a Mac, it would probably be best trying it out first to see what you think of it before purchasing - perhaps even visit an Apple shop to mess around with it. It would be a lot of money to waste on something you may not like using.