80 stamina garden yes, and once your girls are all above level 30. However, the 12 stam garden gives at least one lvl 20 manyu and IS stamina/exp efficient compared to the other two. So with the other two when you are lower level you will barely level at all and thus level your girls more slowly overall since you will need to wait so horridly long for stamina. The 2-1 + garden maps are also good enough at giving you a ton of gold while doing all this.

The 50 garden is a bloody trap, don't even consider it. Once you have a team that can take the 11th or 12th areas and your own levels are high, you can start focusing on the 80 stamina map which, while still not stam/exp efficient, actually gives you more bang for your buck compared to the 50 stamina trash map.

I have never claimed the 2-1 + 12 stamina garden to be a great thing above level 40, but before 40 they are bloody insane and grant you more gold per hour compared to even the gold dailies (per hour, not per stamina, remember that you are still leveling really fast below 40). This while also granting you a ton of manyus.