I have been following professional cherry grafter Ken Coates’ YouTube channel this year . Some of the points that he frequently repeats is that it is important to graft cherries early in the season when both the rootstock and the scions are still dormant. Secondly, larger diameter stiff scions are better. The topmost one to two feet of last years growth is usually flexible pithy wood and it is poorly suited for scion grafting but can possibly be used for budding.
Any type of graft should be fine as long as you have good cambium contact between scion and understock.