I have the Fitbit One, and love that I have the display to see my progress throughout the day. I probably would have went with the Force had it still been on the market. My wife has the Fitbit Flex. I do like the idea of the wristband.
My suggestion is to determine what features your husband would want in his activity tracker. Just be mindful that the Fitbits are made for measuring step-based activities. They may not be so accurate for measuring other types of activity. I make that point since you mentioned doing a lot of farm work. Even so, I still use mine every day. It really does help motivate me to increase my steps and miles. I don't really deal with stairs in my daily routine, but probably would take the stairs more often, too.
On a side note, I currently live in town. My parents live out in the country. I was not really the farming type, but we did raise some livestock (pigs and chickens mostly). I do miss getting out with the animals on a daily basis. I have two dogs, and my family gets out in the yard with them quite a bit. I remember that I sometimes found interacting with the livestock to be more interesting than most things on TV. I'd just go walk out in the lots or woods and observe when I wanted to be outdoors. That's an experience I sometimes miss now that I live in town. Being outdoors in town is just not the same although I do enjoy the parks as much as possible.
