Mechanical beasts will outlast any of the other junk. I have a Cherry keyboard that is still perfectly functional after 20 years of use in the shop. It's looking bad, keys are worn, the plastic is yellowed - but it is still a champ. Great for typing on, tough to beat for data entry style work, with the positive "click" with each keystroke. This is different from the other keyboards, of various qualities. The Acer one we have here is adequate for email and stuff, but is kind of crappy for typing and stuff. The Mac keyboards are even worse, because I have to tear them down and clean them out every year or so - cheap plastics, and that wierd rubber-carbon stuff that is the "contact".
But then, a "cheap" mechanical keyboard can be a disaster as well - there are lots of those around. So it comes down to what you value. If you do lots of typing, or are heavy into gaming, or have to write documents or reports, or have to do keypunch for eight hours a day - nothing beats a high quality mechanical keyboard. But if you are basically doing some email and fooling on Facebook, then it would be overkill.
Of course, price is a factor, but even a $100 keyboard is inexpensive, if you get 10 or 20 years out of it, compared to having a parade of inadequate, cheezy keyboards that save you money but give you carpal tunnel syndrome for the rest of your life.