I've owned a Motobecane Boris the Evil Brut Sprung (yes, that's the name of the bike) for about two years. It costs about $1,700 and is a very solid bike for the money. I use it primarily as a snow bike and run five inch Surly Bud/Lou tires on it. These are massive 26x5 tires with very tall knobs,not great for your usage.

Think about how you're going to ride the bike. Fat bikes vary as widely as regular mountain bikes. Bikes like the Farley and Kona Wozo are very much modern trail bikes with slack head angles, 1x drive trains and very short chainstays. These are great if you're going to use it primarily as a trail bike to rail berms and take jumps. Others like my bike, the RSD Mayor, Advocate Watchman etc are much more suited to snow riding or bikepacking: longer chainstays to help with stability, 2x drive trains to give you ultra-low gearing and steeper head angles to lessen steering slop. Again, it depends how you're going to use the bike.