FE has all the bells and whistles but looks and feels dated in my opinion. WSI Fusion is interesting, but haven't played with it much. Airbus offering something new via NAVBLUE, if you're flying busses might be worth looking into it for synergies sake. Ease of Fuel alert integration will depend on your current ACARS setup - are you getting automated messages, how are they formatted, basically what AOC is on board. FL/Track is easier, as all (I think) products offer integration either with FlightRadar, Flightaware or FAA positions, but if you're flying out of ADS-B/FAA coverage then ease of integration will again depend on your ACARS setup. Basically with ICAO GADSS around the corner you just need to let them know that you're interested, and they'll be at your door in no time offering their presentations etc.