When it comes to manually tracing "organic" objects, such as a tree, I prefer using the pen tool within Adobe Photoshop. The tool works faster and is more responsive than the similar tools in traditional vector drawing programs like Illustrator and CorelDRAW. Vector placement over pixels is precise; it does not shift at all depending on the level of zoom (which does happen in CorelDRAW). Most of all, I prefer Photoshop's pen tool for its keyboard short cuts. Using combinations of the Ctrl, Alt, Shift and Spacebar keys along with the mouse (or Wacom stylus) it's very easy to modify the path while it's being drawn and not have to go to any menus or tool bars AND you can zoom in/out and hand pan the view, again without going to any menus or tool bars. I just with Photoshop had just a couple other vector-based tools, such as anchor point alignment functions.
Adobe Illustrator's pen tool works almost like the pen tool in Photoshop. The keyboard short cuts work in fairly similar fashion. Smart guides lends itself to more technical looking work. Astute Graphics' plug-ins, like Inkscribe, add great new options. The Inkscribe tool is like Illustrator's pen tool on steroids.
For on-screen drawing, I like using various apps on my large iPad Pro. I doesn't cost nearly as much as a Wacom Cintiq screen or computer. The Apple Pencil works very well and charges quickly. I mainly use Adobe's Creative Cloud "mobile" apps, Adobe Sketch and Adobe Draw. Sketch is great for creating pencil sketches that can be beamed into Photoshop or Illustrator to be converted into vector form precisely. Or the image can be brought into Adobe Draw for a more quick and dirty vector-based approach. Something like an organic yet stylized looking vector tree can be created rather quickly in Adobe Draw. Traditional draw programs like Autodesk Graphic and Affinity Designer are available for the iPad at a pretty serious bargain.