Is not that I prefer them in ground,it is that I have a true way to test for adaptability in cold climates like NJ.
Fig trees are not suppose to grow in zone 6 ,but some rare varieties,are stubborn to survive and ripe fruits here and most are not.
I would quote the best adapted to adverse climatic conditions,i have:
Malta Black,ripe early ,produce fruits growing from soil level every time,starting with first or second leaf there will be an incipient fruit.
After 2 years of onslaught frosty climate,some of my "Keeper" cultivars,were refusing to form fruits early in June,this year,but,:
Malta Black is loaded with fruits,in Fact the old original plant and the other 3 younger plants are loaded.
If i had them in containers i would have never know how they perform in cold Winters,because then all of them,are inside ,so all perform the same!
I also grow in ground because of necessity,as I can not handle moving large containers in and out,having ,had back surgery.
Of course your situation could be different,so if you can grow in containers good for you.
Fig trees in containers produce incipient fruits earlier in the Spring,and also can keep Breba fruits ,till ripe so you will have earlier ripe fruits every time.!
I hope this answer your question
Best Regards