I mostly paint on wood panels

[drray23]

since I do plein air. The less expensive canvas ones, especially those on a cardboard backing tend to bend after a few months. Raymar makes some that are top quality but they are expensive.
Instead I use hardboard panels with toned gesso on it ( I paint in oils). I used to make my own but now I just buy Richeson plein air gessoed hardboard panels and they are a good value and stable over time.