The type of knife or cutting tool you buy really depends on what you’re going to use it for. I have several that I use on different occasions.
My first knife was a gift from my brother. He chose it for me because it has a serrated edge, a smooth edge, a flat tip for prying and a nitch for line cutting. It’s titanium and is holding up nicely after a couple hundred saltwater dives. It’s big so I have to wear it on my leg but I recommend looking for a variety of edges if you want something that’s all purpose.
I also have a line cutting tool that I got from Cave Adventurers. (They have a photo on their website.) If your main concern is entanglements, you may want to check it out. I like it because it’s really small - kind of like a razor blade built into a guard. I clip it to my compass or dive watch and wear it on the inside of my wrist.