Geezuz. The old linux v ms v apple debate again!
The best OS is the one you favour. For general use they are all the same. They all have firefox and or chrome. They all have email clients. They all have word processors and spreadsheets. A vanilla install for a non technical user they are all the same. If you have not used one, you will struggle with the other. If you use it for long enough you will learn to understand it.
My advice is always to stick with what you are familiar with. If you want to learn and experiment, then sure, have a crack at another OS. IF you are time poor and not willing to learn, they just stick with what you have. Simple hey?
As for which one is better, well thats all very subjective these days. I use linux, windows and osx. I personally know windows better so I prefer it. But osx and linux are similar (UI exluded) so the transition is easier.