For a liver met, is systemic chemo like irinotecan best or chemo embolization?

It depends. Chemotherapy is the proven best treatment for most such cases . If there is only 1-2 mets, such tumors can be removed and may be curable with combined use chemotherapy and surgery. Chemo-embolization is not a standard treatment, although it has been used effectively by some oncologists. Ask your oncologist the pros and cons of your multiple choices or you should seek a second opinion to explore.