To be honest with you, the best bet is to shop around. All these different supplement houses do not own there own dairies- they buy their whey in bulk from the same source(s) and flavour it and market it how they see fit.
The 'great easy mixing'claims made by some companies is down to artificial additives, not 'triple super duper micro biological filtration unique to our labs'.
When it comes to whey supplementation you have two criteria to consider, and their relevant importance to you will factor in your choice.
1. If you dont care about the taste, and are happy to glug it down no matter how vile, then just go for what is on special offer, or even better, buy in bulk from the whey consortium. unflavoured, non-marketed plain whey powder. 40lbs used to be the minimum order. Add your own flavouring.
2. If taste and a packaging that makes you go 'ooh!' is important, then the world is your oyster. I like 'ON gold standard' cookies and cream because its yummy, but I use it sparingly as a treat, i dont have the cash to make it part of my daily eating regime.
Member 'Grumbleweed' has taken himself from a corpulent 17 stone couch potatoe to a crazy-lean 12 stone hardbody crosstraining freak on a heady combination of hard work, determination and Holland Barrets finest bargain basement whey and the odd egg and milk home made shake.
Protein is protein. Hard work is hard work. invest more in the latter than the former.