Wanner is the best you can get, I have tried others included ones operated by compressed air and nothing comes close to a Wanner. Not cheap but new are available but consider the cost of seized kingpins? I would advise you go for a 2 bleed screw model, one screw vents the grease chamber and the other drops the pressure down incase you get a hydraulic lock on the grease nipple, and these guns are powerful enough to do that.
You will leave it to your dependants and it will still work perfectly, mine is 30 years old and still faultless.
