Just get the one with the most power for the cheapest price. These days they're so cheap if you need to buy one every couple of years, you're fine.
Oddly mine's almost 10 years old, gets used several times a day and the sucker just keeps running. I want a new one but I can't rationalize it until this one dies on me. It's a Panasonic if that helps you find one that will last forever
