All reloaders are simple and easy to use as everything has a learning curve for us all...the models which turn out a shell with each handle pull are my choice....depends upon what level of reloader you need.
The lowest MEC model will turn out a fine shell...I do prefer the brass resizing feature tho.
Some reloaders are easier to clean when one spills shot or powder, to me.
For me, MEC is easy to use, easy to adjust, easy to clean and turns out a good shell.
Parts are readily available from MEC and, imo, reasonable in price.
But, most others do fine...some makes, like PW, have a bit of panache
...but, add refinements, features, hydraulics and complexity, et al follows.
What wears out?
There are some rubber grommets in the bar that can wear, shot side especially...same with the little brass washer.
Anything that moves will wear....but it can pretty much all be made new again.
Hard to say about buying used tho...w/o seeing it, trust is involved.
Look on a MEC dealer site at the prices for repair/replacement parts to get an idea....call MEC if you have a question.
MECs should be painted grey rather than red.....gray being the color of a battleship.
There is a point where a bit more in $$$s spent is well worth it in the long run.
Good luck.
Buy a reloading manual!