I carry a Spyderco Eudura. But a lot of firefighters and police officers I see carry Benchmade switchblades. These Benchmade knifes are extremly common. Automatic knives are often seen because contrary to the legal blissninies, you often don't have two hands to open a knife or one hand is covered with blood that you don't want to get all over yourself. The nice thing about the Spyderco is that being all stainless, you can wash it or even autoclave it.
In reality, for heavy cutting, I have a pair of big shears that I carry on a fanny pack. I would have to get back to you on who makes them, but they are fairly expensive and will cut anything. I once went on a shooting call; cut the guys pants off and in the process cut through everything in his pocket including a few thousand in cash. These big shears are extremly common also. I am not talking about the ones you get for $5.00 at the gunshow or the flea market although to be honest those are almost as good. These are very high quality and cost close to $100.