I would be most concerned about testing of the milk if you are going to use it raw. The feed materials and living environment may impact the flavor, but unsafe milk will impact your health. I doubt that the distant surroundings like cell towers, quarry or cement plant will have any impact.
Renais

I would pick the one with enough liability insurance that you can sue them for the hospital bills if you or your children get listeria, E coli or any other milk-borne illness. But I'm a cynic.

You don't seem to know much about the milking process or where bacteria can get in ...

I'm assuming a manual milking machine ... How do they disinfect the machine's cups between cows? How often do they clean the lines with live steam?

How fast can they chill the milk?

Ask about the health and sanitation practices of the people doing the milking ... do they wash their hands between putting the milking machine on each cow? Do they stay away from the milking process if they have an infected cut, chapped hands, or a sore throat? Do they ever touch their face after washing hands between cows without washing hands again?

Do they manually strip the udders after the milking machine? If so, how do they sanitize their hands before doing this.

What is their process for handling a cow with mastitis? How is she isolated from the milking herd? And for how long?

NOTE: IN this epidemic, the source was a dairy worker who infected a cow ...
http://www.foodsafetynews.com/2011/12/portlands-best-raw-milk-dairy-killed-22-in-1922/

Not sure if you are checking further here for answers......There is some good advice here but I do not believe in looking at whether someone has a large enough insurance policy. YOU are responsible for what you choose to eat or drink, and YOU are responsible for making an informed choice. I don't understand the "sue mentality". If you need to think that way then the farm in question isn't the right one.

Tour any farm you are considering doing business with. Ask tons of questions. The farm and animals should be spotless. I mean 100% spotless.

Ideally the cattle should be 100 % grass fed, with fresh pasture rotation on a daily basis. For a couple of months in the winter the cows are fed high quality hay. At all times the cattle are fed balanced minerals. Tour the farms, ask questions, and decide if you are totally comfortable with the cleanliness of the farm and milk handling. Then develop a relationship with them.

Clean raw milk is one of the most healthy and delicious foods, if handled correctly. Also, cows were never meant to eat grain. They are not grain animals. They are grass animals. Grain alters their chemistry, and not for the better.

Factory farms are disgustingly filthy and cruel. This is where your store bought milk comes from (and store eggs and meat as well...yuck). There are more illnesses from so called inspected pasteurized store milk than from any good clean raw milk grass fed farm. I would go completely without milk before spending one nickel on a gallon of milk from the store ever again. It is revolting in taste to me.

It is worth the drive if necessary to find the right farm. "Somewhat untidy" and "relatively clean" is NOT good enough. You can also pasteurize milk at home by heating it up in a kettle, if you wanted it pasteurized.

Look here:

Here is a link that might be useful: Raw milk - Campylobacter outbreak - 38 football players sickened

I am assuming you've since made your decision but if not having grown up on a small 50 cow dairy farm these would be my requirements.

You definitely need too see the tests. Most raw milk farms are not required to test as frequently as conventional farms who sell whole sale but I would like to see one which test at least weekly.

Second is your cream content, your typically going to get more cream from jerseys but that might fluctuate a great deal when the graze on the spring flush vs winter hay.

Second is overall cleanliness of the milking herd. If there outside on pasture how muddy is it or are they rotating frequently into clean pasture.

Looks like you've already looked at the storage just be sure to confirm the milk is kept below 42 degrees.

Hope this helped if you are still debating.

I would check out http://www.realmilk.org and also you can also email questions to the people at http://www.westonaprice.org for unbiased and truthful information about raw milk, pasteurized milk, cleanliness, milk certifications, how to spot bad milk (raw milk anyway, pasteurized can be contaminated and you won't be able to tell), the lies that are told by the media and govt officials, etc etc etc. An excellent book if you are so inclined to read about the history of raw milk in this country as well as the world is "The untold story of Milk" by Ron Schmid. A good one is by Dr. William Campbell Douglass III isThe Raw Truth about Milk.

Hope this helps!