Most of my grafts are on existing trees. Only 6 are on rootstocks.
Apricot. 4/3 (2 of the failed 3 were Amadiocot)
Cherry. 7/0 (5 died with the Black Srar that died)
E plum. 17/1
J plum. 5/0
Pluot. 3/2. ( the failed 2 were frozen scions)
Peach. 5/3 (the failed 2 were Galaxy, perfect scions but failed two years in a row)
A pear. 3/0
E pear 14/1
Paw paw. 1/0
In my experience, the easiest to graft are apple and pear
Then, plum/ pluots
Then, cherry and apricot
Peach is challenging. ( So far nectarines has been easy for me)
Not sure about pawpaw but persimmon can be challenging.