Question Which one of these laptop fans is better at cooling ?

How long does a fan last ? I have already replaced my laptop's fan with a brand new delta fan...should I buy one for backup ?
It really depends on it's conditions. how fast it goes, how stable the power to it is, how much it works, how much dust is in the air, where it is placed, temperature.

I've seen fans last 7 or more years, and some that last a couple of months (they were defective obviously, but you get the point).
I probably won't bother getting a new fan since by the time it dies your laptop will be useless.