The "con" to nucs are really just if the nuc is not on the frame size, or cell size, or comb size you want. In other words, if you can buy a nuc that is the size and comb type you want a nuc is probably the best. But if you want mediums, you have to find a medium depth nuc. If you want small cell, you'd need to find a small cell nuc. If you want a top bar hive, you need either combs that fit your top bar hive. If you can't get these, then a package is the best. The bees will build on the size frame you give them and you'll have bees in the right equipment.