Responses clearly show the best choice depends on what threat you might encounter, with the biggest being a griz of some flavor, and perhaps the most dangerous being a man intending harm. Seems a crazy fishing endeavor, or at least a shame, where truly dangerous people must be considered, but it is what it is.
I'd take plinking out of the equation. YMMV, but if I'm fishing, I'm fishing. But if small game is a consideration, then plinking of a sort is back on the table.
If snakes are the only consideration, then a question is are you shooting at any "bad" snakes you see, or only those that somehow wind up too close for comfort. If the latter, I'd seriously consider a shot load of some kind.
If not fishing, but hunting, then is your primary a rifle or shotgun, how big, yada, yada, yada.
Edit to add: The OP was too broad a question, but perhaps he was looking for things to consider in addition to guns to consider.
I don’t know about the OP’s area but the lake where I take my boy fishing all the time has a network of two tracks around it that crisscross through some seriously overgrown and wild areas. It’s only 2 miles from town but rather wild and secluded due to overgrowth and rough and rutted access. Methheads love these kind of places to set up mobile labs which they don’t like people snooping around. We haven’t found anything and don’t go looking for it and keep to ourselves when we see people down there, but I do know guys who’ve stumbled onto these type of operations around here. For that reason I always have some kind f centerfire handgun with me and more often than not an AR and a few mags. I’m not going to quit fishing because of them but I’ll darn sure go prepared to deal with some weirdo.
