Depends really but what you mean by low maintenance. I have a bit of a zoo lol so I can testify what it's like to own many of the let's listed.
I have, two cats (and indoor one and an outdoor one, that sounds a big weird writing it down 😂), tropical fish, goldfish, turtles, an African land snail, bearded dragon, snake and we had a hamster but he died (natural causes) in the summer.
The easiest of my zoo, is the outdoor cat, she turned up as a stray and after weeks of hunting for owners, we noticed she has worms and vet said we could either keep her or hand her over for re-homing (vets has checked for chip and done searches for us too). So out outdoors car is really easy, she goes out to the toilet so no mess in the house to deal with, we do have to have someone watch her when away as she likes wet food I'm comparison to our indoor cat who we just leave a massive bowl of food down for. But she's easy. She has a cat flap so comes and goes as she pleases, she's mostly in these days.
Next easiest, probably the snake but i doubt that's the answer your looking for.
Land snail needs Frey's veg everyday, sprayed twice a day to keep humidity levels up, clean water everyday, and I replace the soil about monthly.
Fish wise, my tropical tank is bigger and therefore the greater the volume the less maintenance but not an ideal pet for children as they require knowledge about maintaining water quality and are fairly boring really.