G&S and DFS Farming systems
As far as I know, there are two farming systems in Second Life that are really fun to farm they are the G&S system and the DFS system. I have tried them both and my favourite system which I find the easiest is the G&S system.
Both farming systems can keep you occupied for hours both have a lot for you to do in order to farm and have fun, but however both systems do have its disadvantages one of them for both systems is where you have to buy some of the game items and animals in order to farm which can be quite costly.
Another disadvantage is in both systems you need to have energy in order to farm and do tasks which can be quite annoying when you are starting out in farming because you tend to run out of energy quite fast and always have to find ways to keep getting more energy to continue.
However no matter the disadvantages you eventually gain it all back over time when you master how to farm and make foods and gather resources, so in the end, it is worth it for the fun factor and having something to do in Second Life when your really bored.
There is always something new coming out in the farming systems so if you get bored of the system it will not be for very long, the creators are always coming up with new items to extend the farming play. There is a lot to learn when you start, but luckily they have groups you can join and there is always someone you can ask on how to do something if you are not sure these members have been doing it from the very beginning who can definitely help answer your questions.
So if you have the Lindens and the time then I definitely recommend these systems for you to try and have fun.