Nabil, these 2 trees are only good as garden trees. They would look very pretty in a large pot on your patio. Every garden should have a red maple. So if you don't have a red Japanese maple, then one of these would be good for you. It is good because you will learn how to take care of it and learn to enjoy and appreciate it for what it is as a natural tree. It does not have to be a bonsai for it to be beautiful. It is also good for you to use it later to take cuttings or layerings from and to collect seeds from.
These 2 trees are not good to chop down for bonsai training. The graft sites are very ugly on both trees. You will never be able to correct that ugly graft site. I would recommend that you don't waste your time trying to train these trees into bonsai. You could get a nicer bonsai in ten years if you buy one of these trees, grow it out in the ground as a garden tree, collect the seeds, then grow the seeds into a bonsai. Or you could just buy some seeds or small seedlings and start bonsai from there. Developing a Japanese maple bonsai (and most other deciduous trees) is better and faster when started from small seedlings and grow up rather than started as a big tree to chop down.
Good luck!