I mainly use Bristol, but it becomes wavy after a few coats of water. I have some regular watercolor paper, but I'm not a fan of the roughness of it.
Are there other types of watercolor paper I should be aware of?
Sounds like you're seeking something you'll have more control painting on. Try Arches 140LB hotpress ..tape it to masonite with moistened gummed paper tape. Don't let the water from the wet tape get on your paper though because it'll dry clear but repel pigment so, before sticking tape to the paper-edges on the board, shake the excess water off the tape AWAY from your piece of paper THEN adhere it. Smooth the tape flat with your hands, being careful to not swoop any water ONTO your paper.
Let it dry &, when it is & the paper's taut, commence painting. Tip. Draw VERY lightly your plan on the paper beforehand. That way, after painting, (& all paint is dry) you can erase the lines with a white or gum/kneadable eraser. Never erase on damp paper. It'll eat into the sizing.
There is cold pressed water colour paper and hot pressed. Cold pressed has some texture to it. If you like a smoother paper, get the hot pressed, it has a much smoother texture.
Id suggest getting artist grade papers in at least 140lb. I like both Arches and Fabriano Artistico Hot Pressed 140lb. If you buy paper in the large sheets from an art store and cut it down to size it ends up being a better value.
Ive has some luck with the Fabriano Artistico Studio grade paper in pads, it comes in both cold pressed and hot pressed. Its a great quality paper for practice and learning and is a bit cheaper than the artist grade papers.
Steve (The Mind of Watercolor) on YouTube uploaded the "SHOWDOWN! Cheap vs Good Quality Watercolor Paper" video last March in which he compared several watercolor papers against the brand he prefers to see how the paint behaves on each one.
As part of his comparison, he briefly explained that buckling is caused by lighter weight paper, so you'll want heavier paper to prevent the buckling, regardless of brand.
He also demonstrated the difference in how the types of paper absorb and disperse the water. You might want cotton paper since it disperses the water quickly and evenly.
Another thing he discussed was how the smoothness of the paper affects the behavior of some paint, so since you you mentioned not liking the roughness of the your paper, you might want to give that part a look as well to see whether smoother paper would work well with the types of paint you use and/or the effects you're after.
In addition to the paper weight, content, and texture (as discussed in Little Girl's answer, each of these factors definitely plays a huge role in how the paint responds to the paper, and how the paper responds to the paint), you can also physically fasten down the paper or stretch it to keep it flat. You could physically tape the paper down to a flat surface prior to painting using water color paper tape, or blue painter's tape, and then remove the tape after the painting has dried. Some water color paper blocks have each page glued down along the edges to each other, which produces the same effect. This blog (http://somecallmebeth.com/keep-watercolor-paper-warping) offers some useful tips and videos on different methods of stretching/taping paper to keep it from warping.
If you have a finished, dried painting that is buckled that you'd like to flatten out, this blog provides some useful information: https://www.strathmoreartist.com/blog-reader/how-to-flatten-a-buckled-painting.html
Generally there are 3 kinds of water color paper 1.hot-pressed watercolor paper 2.Cold-pressed watercolor paper 3. Rough water color paper
Hot pressed is smooth paper with no bumps on it. It is a super fine paper, with grains that are plain and smooth. It is easier to paint on the hot-pressed paper because there are no bumps. Moreover, the hot-pressed paper is ideal to paint for larger and even strokes.
A cold-pressed watercolor paper is slightly grainy. It is not as smooth as the hot-pressed paper. If you are looking for a textured surface to paint on, the cold-pressed paper is perfect in that case.
Rough and cold-pressed papers are similar in a way that both of them are grainy. However, the rough paper has bigger pumps and the absorption of the watercolor is much easier on the rough watercolor paper.
In this blog they have mentioned different kinds of water color paper:https://allpaperworld.com/best-watercolor-paper-brand/
The main difference between the hot and cold press paper is of the graininess. The hot-pressed paper is smooth. However, the cold-pressed watercolor paper has grains and bumps. The hot-pressed watercolor paper refers to a more smooth texture and finish. Whereas, the cold-pressed watercolor paper is coarse paper with a bumpy finish.