Furniture because my house (and town) needs to look amazing. Not too bothered about museum stuff (althought I love collecting them) since I don't go to the museum to browse very often.
Fishing in the ocean has always been my way of making a lot of bells quickly. I was way too lazy to do the stalk market, and bugs high-priced bugs are pretty rare and hard to catch.
I prefer catching bugs. With fish and fossils, you never know what you're going to get until after you've caught it/gotten it assessed. With bugs, you can see the bug and know exactly what you're going to get... if you can get it.
I fish and I fish even when I don't want to. I don't have a net yet. I don't keep the fish usually but I do keep the furniture most of the time. I'd love to have a room of gyroids and sculptures, though. It just sounds like a unique idea.
I voted "Other". Fish is a huge one for me, but my main collection is clothes. I await each day with fervor wondering what the Able Sisters will have in stock for me.