Algorithm for a pizza shop, Which one is better??

Question

Hey there, i want to write an algorithm for a pizza shop (c#)

 

i wrote and i showed it to my friend, my friend said: your algorithm is wrong. and he wrote another algorithm.

 

and right now i want to know which one of our algorithm is better?

 

please download the zip file (that's my source sode), and open the"Program.cs" file, then, tell me which one is better and correct? (with reason)