apple tree from seed died but it has sprouts! wondering how to encourage them?

Our ten year old trip apple...a newton pippen...did not survive the apple tree borers.

I grew it from seed brought back from an apple that was from a farmers market on the west coast during a long train trip....posted about it here https://permies.com/t/220433/Apple-tree-seed-planted-apples
We have frequent borer damage on peaches and blackberries and apples and I'm working on some prevention methods.

My question, though, is about the sprouts clearly coming from this apples roots, maybe 10 or so?

Shall I thin them?
Leave them all and select later?
Pull or cut one and try to root?

Because I experiment by planting various species and cultivars I frequently end up with dead scions and rootstock surviving. I have five plums and four such apples. If the growth is strong I keep them and do nothing (except regular irrigation). Plums are on Myrobalam or American plum rootstock so I expect to have fruits. Apples were on Antonovka, but now I'm not sure what will be the outcome. Several years ago I have planted four Antonovka rootstocks - one died, the other two did not survived grafting, but still regrew from the root and the fourth one got quite large and finally produced fruits, but they do not look like Antonovka at all, but hopefully will taste good and if not I will still use them for processing.
You can select the strongest one and later graft or not. You can also leave them as they are and they will grow into multi branched tree. If you are in apple growing region, keeping an unknown apple may not be worth. I'm in a region where apples rather suffer, so I will be happy with anything.