I probably have more than 5, but here are the big ones.
1.) Taurus, or anything cheaper.
- Reasoning: To me, a gun represents more than something to run to the range with and throw a few rounds downrange with. To me, a gun is an investment. My family takes good care of guns, and we still have guns in marvelous condition that have passed several generations (including some real gems like a Colt Python). When I buy, I buy for keeps. I never intend to sell or trade a gun unless financial straits become dire. Further, it is a MUST that I can trust, absolutely, every gun I own. I know that each and every one of my guns, when properly cleaned and oiled, will perform 100% when I need them. Taurus, Bersa, Jennings, etc., and other such "budget" guns represent a far poorer value than the few hundred dollars in savings equates to. It's a gun you can never completely trust, which to me renders it useless. I love Ruger, but Ruger is NOT cheap. Ruger is INEXPENSIVE. The difference is in quality, and Rugers are tanks. Same with the Remington 870. 300 bucks buys you a brick house.
2.) Derringers
- Reasoning: Why? There are tiny guns now that can deliver outstanding power and reasonable round counts in a tiny package. The Ruger LCP and Khar PM9 are good examples of this. Derringers are a relic that really don't have a place anymore.
3.) Pistol-grip shotguns or machine pistols
- Reasoning: Much like the derringer, there are guns that can do what these guns do much better with no appreciable loss of function.
4.) Taurus Judge, S&W Governor, etc.
- Reasoning: I can't stand these abominations. A giant, clunky gun that does two things and does them both relatively poorly. A .45 by itself could do the same work in a smaller package, and the .410 is a god awful self defense choice.
5.) DAO/SAO firearms
- Reasoning; I enjoy the versatility of DA/SA in semi autos - it provides for safe carry with no manual safety followed by rapid followups. Revolvers, I also like the DA/SA hammer, as it makes the gun more adjustable to the shooter. To me, all DAO or SAO firearms do is limit options
- Exceptions: Glocks (technically DAO but a very good "Safe Action" trigger), and Cowboy-style shooters (Ruger Blackhawk, etc.).