all depends on the policy of the firms you are dealing with. A wire requires the receiving firm to physical inspect the transaction, so the firm obviously feels secure about guaranteeing it. It is physically slower though. iIdo not know about others, but for me, an ACH is always available to use the next day when I send it from IB to my bank. And it is free.
So has anyone seen any other futures brokers besides IB with ACH transfer option available? Wire transfers get too expensive when shuffling funds between accounts...