Keep in mind that if you fly El Al NYC-TLV that you have to be on a Delta-issued codeshare ticket to get any MQMs at all. Moreover, if you buy a reduced rate fare from El Al directly you will only get half the SkyMiles.

On the other hand, you can get a Biz ticket from Delta and get 20,000 MQM's -- almost certainly enough to get you to the next highest medallion level.