Would.

Student or Learner
Hi all,
A : Are you sure Mark is coming to the party?
B-1: He told me yesterday that he would come.
B-2: He told me yesterday that he will come.
In the context above, which do you think is better, will or would?
OP
What if Persons A and B are talking today and the party will be held tomorrow?
Even if the party is held in the future, will "would" be better in the reported speech?
OP
I don't think this is a question of which is better, because they are both used in slightly different ways. The fact that the party is in the future doesn't affect this.
Without going into cases where I think will could be preferable, I'll just say that would is more likely.
I can't think of a context where will would be natural in American English.
I am not a teacher.