For what it's worth, the only blender I've managed to not kill (making frozen drinks, which is very hard on the motors) is a KitchenAid, with its whopping 500W motor. It's not the most expensive blender I've killed, nor the one with the highest wattage. What it has is a good jar design, and enough smarts in the electronics to soft-start and supposedly do motor control when it encounters excessive resistance. End result? Smooth daiquiris without lumps, and the thing works like new.
I did have to replace the coupler (the rubber toothed gear that connects to the jar) at year 6. I'm OK with $10 every 6 years.