Which carries greater reward with Allah: spending money to perform 'Umrah in the month of Sha'ban, or setting up an Iftar table (Ma'idat al-Rahman) in Ramadan?

If this is your first 'Umrah, then you are obligated to perform it with this money, because 'Umrah is obligatory according to the most authoritative scholarly opinions. However, if you have performed 'Umrah before, then feeding fasting people is preferable, due to the great reward and recompense it entails and the widespread benefit it offers to others, especially if they are poor. For whoever feeds a fasting person will receive a reward similar to theirs.