good thickness for wetsuit

Hey guys,
getting ready to buy a wetsuit for rf fishing in north cal water. Looking at a farmer jon from  nrs or kokatat.  What would be a good thickness to get?are  there  any other brands that worth looking at?
2mm,3mm? Don't plan on diving in.

3 mil is good enough for me in all bit the coldest days. On very cold days I ware a dry top over my farmer John. I also like thicker booties, I think my booties are 5 mil.

Allot of people recommend the 3mil FJ from NRS with a relief zipper and add a windproof top

I don't think that's thick enough for safety in a longterm immersion scenario.  It doesn't happen often but it does happen. There's an excellent cold water immersion video in the safety section.

I have a 5mil FJ that I put a relief zipper in and wear a 3mil jacket with it.  Then add windproofing if it's cold.

Ken, also I have a skinny guy's wetsuit. I used it before i put on an additional 40lbs. It is more of a dive suit, a 5 mil 2 piece farmer John and jacket. If you are about 160 lbs or less and less than 5 feet 7 inches tall, I'll give you this suit for the cost of shipping.

Thanks for the replies.
Thanks for the suit birddog, Unfortunately I don't think I'll fit that suit.
Ken