The biggest difference between having the 33 or the AK is:
If you hold the 33, you have to worry for all 5 flop cards.
If you hold the AK, you have to hope for all 5 flop cards.
For myself, I much prefer to hope rather than worry... and for this reason I always want the AK instead of the 33, even tho I fully understand the 33 is actually a slight favorite over the AK, preflop all-in. This is why I am never afraid to shove all-in with just AK, because it is a hopeful shove.

I won't do it every time, for instance it is very stupid to shove all-in during first level of the tournament at 10-20 blinds when we have 35,000 chip starting stack.

But if it is a "reasonable" shove, then I have no worry shoving AK, I only have hope!