By dumping I presume you mean transferring from Amex or hotel or other credit card scheme, as opposed to earning by flying? (If the latter then different earn rates of programs will matter).

If so then also need to consider - can be transfers be done at all? what transfer rate inclusive of any bonuses (not all are 1:1)? maximum amount able to be transferred at once? maximum amount able to be transferred over a period? any fees for transfer? cost of awards varies - 120k miles will get you much further on some FFPs and not very far at all (in F) on other FFPs, etc.