I am one of the lucky one's soon to be off on my third cruise this year, each cruise is different. I have been on a few back to backs so I can confirm even from one week to the next the whole atmosphere of the ship can change.
To me the best line for consistent level of service is Royal Caribbean, I have even had the same waiter on three cruises on two different ships how lucky is that.
She even remembered what wine I like and that my wife only drinks occasionally and then its Asti.
I hear this argument about tips across many forums the crew have different wage structures on different shipping lines. There are lines that include tips others don't so when you book a cruise it is for you to factor the tips into the price if you can't afford the cruise with tips then look for another don't fleece the people who make your holiday special.