CBO most of the time with ad set limits to ensure ad sets with lower audience sizes still get served. Ad set limits are critical in retargeting but I find results can be good with or without them for prospecting depending on budget, audience sizes, etc. I do still like using ABO for testing new audiences sometimes. one common example that I do for e-commerce is take press quotes from well known publications about the brand, create several ad variations that include that quote somewhere (creative, copy, or both) along with the product and then put it in ABO ad set targeting that publication as an interest.