Like with all things, it depends on what you want. Here are some pros and cons:
Fisherman - fishing takes a long time to level, primarily because you can fail an attempt and get no xp. That said, when you (rarely, and I mean really rarely) catch a rare fish, they usually sell for good money. If it's a fish used in the Sucker Set, this can be up to 2 million kamas, depending on your server, timing, current demand, etc. If you are a dragoturkey breeder, the fish can also provide energy for your mounts, which can be useful. Fish is fairly heavy, although not as bad as wood or ore, so consider getting some pod gear or taking this as a second or third job if you don't have a strength character.
Farmer - bread is the almost universal health food of choice and the rare stat breads can be useful. A high level farmer should be able to make consistent money, if not insane money, from high level breads. Also, the ability to harvest rice provides a nice synergy with alchemists, below, who can use the rice for bontarian and brakmarian teleport potions.
Alchemist - alchemy is easy to level, since gathering and creating are the same job. That said, it does not make incredible amounts of money and the recipes often take large quantities of ingredients. It can be good for a new character who is non-strength to get some pods quickly since it's easy to level. If you PvP frequently, the ability to make both hp restoration potions and energy replenishment potions is useful. If you like crafting weapons, the alchemist can also make the potions to change the element on a neutral weapon.
Hope that helps.