Some caulking guns do have some nifty new details on some of them, like a knife for cutting off the tip of the cartridge or wires to poke holes in the tubes.
I don't know why, but the wires are often not long enough to do the job if you cut just a little bit off of the tip. Bad planning. (Years later I had a chat with the Taiwanese manufacturer of most of the caulking guns sold in North America and he had no idea that Canada's LePage products tended to have longer nozels than everyone else -- he promised me an extra inch on that wire but I have never seen it. )
The Strength Zone for the ratchet
The two ends of the gun are the most important things to look at when buying a gun. The old ratchet with click-click notches, like in the first photo are the worst kind of gun you can buy. You have to squeeze the handle all the way to the next click, and with some thick or cold caulking and a tired hand, that can mean that you are squeezing way out of the strength position of your hand. For each hand, there is a small zone of grip where it is easy to squeeze. A more open hand, or a more closed hand is not as strong. The ratchet grip often forces you beyond your strongest position.The gripping mechanism on a smooth shaft allows you to start your squeeze from any position and stop at any position, keeping your grip only in your strongest position.
The resistance of the retaining ring
At the other end of the gun, the basket type is the cheapest of the guns, and if you use it much you will discover that cheapness results in the front end bending forward or even breaking off the spot welds, rendering the gun almost useless. Unfortunately it still works a bit and you are too cheap to simply scrap it but your frustration level is rising rapidly. A good and reliable gun will have two straps, and the best of the straps will not only be welded to the front ring, but bent over so that there is no stress on the welds.
Video on how to caulk and why
Yes I am particular about my caulking guns. When I am doing a job that is not necessarially enjoyable, I don't want my tools making it even worse. Check out my building science animation on how to caulk.