I would bet dwarf citrus fruits would be the easiest for novice gardeners in southern states. I'm assuming you mean southern states of the United States. I think citrus dwarfs work in any of the southern states west of the Mississippi. Dwarfs don't like to be cold and dwarfs don't like to be wet all the time. Plus, there is not a lot of pruning involved, so novices like that a lot. But, beware, dwarfs can grow as tall as a regular tree if not treated like a dwarf. There is some strategy involved with keeping the dwarf small, but it's all good and easy. I have a dwarf lemon and a dwarf orange tree. I grow each of them in a large container with rollers. In the summertime, I move them to the area of my garden that gets sun for most of the day and shade for some of the day. In the wintertime, I move the trees to an area that is protected from harsh winds. Dwarfs need to be babied that way. Some people actually bring their dwarfs into the house in the wintertime. I keep them outside and they seem to be doing just fine.