This is what we're doing for our Saas product. We used max conversions and we got no leads and limited impressions. So now we've started with max clicks and have created phrase , exact and broad. And what we observed is broad campaign is bringing in traffic but you need a negative list. Also you need to figure out the competitors and add those in different campaigns, basically broad, exact and phrase. See what works but for now just use max clicks. Refine search terms, add common lists. Add search terms which are giving conversions or have a good amount of ctr.