What is wrong with this picture? All this talk about this grease gun or that grease gun and NO DISCUSSION about the really important thing.... GREASE!
It makes absolutely no difference what grease gun you choose if you dont pump the correct tyupe of grease for the job! Read your manuals.
About grease: NEVER MIX DIFFERENT TYPES OF GREASE. Greases are oil (usually fortified with additives to enhance particular performance demands) and the oil is held in suspension in a metallic SOAP. That soap is based upon different concoctions of metallic salts such as Lithium, Calcium, Aluminum, etc etc. It is important to NEVER MIX DIFFERENT TYPES because they do not mix and lubrication will suffer causing galling and bearing/bushing failures.
In addition, not all greases serve the same purpose. For example, wheel bearings, roller bearings, ball bearings all work well with lithium, OR Calcium, OR aluminum base soaps. But your Front End Loader has plain bushings and pins that rotate on each other under extreme pressure and its likely your manual demands that you use MOLY type grease. (Molybdenum is an additive that stands up to severe shear loading and is preferred for such use. But it does not do as well as other base soaps for roller bearing use. In another example, sulfonate greases are particularly suited for water washout resistance while Moly greases do not, one of the reasons your mfrr recommends lubricating your FEL with MOLY grease every TEN HOURS. Such frequency is not necessary with other base soaps.)
Synthetic greases are not necessary for items requiring frequent greasing, and synthetics should not be mixed with non-synthetics. If you change from one type to another then ALL the old grease must be removed before the change.
Do your research. Use the appropriate grease for the specific task at hand and DO NOT MIX DIFFERENT TYPES OF GREASE.
(I use manual grease guns with flexible hoses and I have FOUR different guns each clearly labelled for the particular type grease cartridge inside it. Since Lithium is widely available and perhaps the most commonly found I use it for general purpose chassis grease. I use Moly for plain bushings/pins like the FEL. I use a Marine Boat Trailer Bearing Grease (water resistant, either calcium or aluminum but never mixing them, for all wheel bearings. Those are my personal choices. You can choose your own, but NEVER MIX DIFFERENT GREASES and read your Owners and Service Manuals if you want your equipment to last.)
It makes very little difference what kind of grease gun you choose, but it makes ALL the difference what type grease you choose.