Ants are extremely hardworking creatures. They’re insects with qualities I really admire, but because they’re often killed by people for wandering around at the dinner table (and too close to the stew), I wouldn’t want to be reincarnated as one in my next life. That is, if I believed in reincarnation, but I’m still iffy about it at this point.
Regardless, I would think that the awesomest way to come back on Earth would be as a tree. Preferably a huge one that people wouldn’t want to cut down ever. If you have the same notion, then you might want to check the Spiritree out.