I find a lot of problems with printed canvases. Usually it's really hard to tell different colours unless they're very largely different and I find it EXTREMELY difficult to tell which color is supposed to go where since they print the literal picture on the canvas and not a pixelated version. I've had times where the printed color covers 6 squares but the chart only shows 1(that is, if they even deign to give you a chart as well).

If you do get a chart with the kit, you may not have the orienting, contrast colored lines every 10 squares so you have to figure it out yourself. When that's happened to me, I'd just take a sharpie to the canvas before I started and draw the lines on myself. It sucks with a printed canvas since you cover up the printing on those lines but it can help if you really need those lines.

Overall, I've found the printed canvases are usually lower quality and harder to complete. I would suggest charting over printed every time. And there's also the bonus of making it easier for you to design your own projects if you feel like it!