What's better to use in Iphone: Home button or Sleep/Wake button?

I recently discovered the "Assistive touch" feature in the Iphone and it is a good substitute for all the physical functions of the Iphone including the home button, I've been using it instead of the home button for closing apps and other stuffs.

My problem is that I used the Sleep/Wake Button whenever I want to turn the screen of the Iphone ON so I can used the "Assistive touch" button on the screen, does the Sleep/Wake button wear faster than the Home button or is it the other way around? Does using "Assistive touch" instead of the Home button a good move or not?

I just got my iPhone and I was confused on 2 things. What is the difference between the main round button on the front vs the Sleep/Wake button all the way up on the top? When I want to acces my iPhone generally which one should be pressed or is it just common preference?