well, it depends.

Kefir is better than yoghurt, much better, wider variety of microorganisms and more concentrated so you don't have to eat as much milk sugars.

Candida people tho need to replace not just acidophilus but also soil-based organisms. So to be thorough, you need something like Primal Defense AND live acidophilus, from either kefir or pills. And things like cabbage rejuvelac, apple cider vinegar, have their advantages too.