There are several arguments given for gun ownership and each reason favors a particular type of gun. Some people may feel they need them for self-defense because they live in places they think are dangerous or are particularly fearful for their safety. Other use them for hunting. The ones that cause the most controversy are the high-powered, fast-action ones like the AR-15 or the AK-47 that can fire many rounds very rapidly and thus can cause many deaths in a short time. These weapons are primarily designed for military uses.
The debate over guns in the US, like most things, tends to be split along left-right lines. Those who oppose pretty much any restrictions of the right to own and carry and use guns of all types tend to be on the political right. The National Rifle Association is the group most publicly identified with this hardline position but I learned that there is another group called the Gun Owners of America that takes an even harder line and boasts that it is “The only non-compromise lobby in Washington”.