It depends in most cases it would be a FC.When there is an IF hit and the defense ignores the batter, goes for the lead runner and fails. Everyone is safe. Is it scored a Fielders Choice?
I have always scored it that way, but someone was just telling me it's not an FC unless an out is made.
If in the official scorers opinion the batter would have been safe at 1B even if the fielder tried to make a play on her instead of the lead runner it would be a 1B instead of a FC.
One example might be ball deep in the hole at SS; SS tries for lead runner at 2B but is safe. If it would have taken an exceptional throw to get runner at 1B that's likely an IF hit.
If on the other had it would have been a routine play at 1B but SS tried to get lead runner at 2B and did not it would be a FC.