I have 2 cats, 1 axolotl, 5 guppies and their babies, 1 bearded dragon, and the rest of my house has 7 more cats, 2 dogs, and 2 chinchillas.
I would recommend a 20 gallon freshwater fishtank for you. Make sure to cycle it first or use live material to jump-start it.
Why ? It's virtually nothing to do apart from feeding them. Once cycled you clean it every week (unless you've overstocked) - and that's just... sticking a siphon into the gravel and squeezing the filter into the recently-siphoned water every few weeks as necessary.
I recommend 20 gallons because trust me, it's easier. A fishbowl is cruel and MUCH HARDER to take care of. 10 gallons is iffy - my guppies are in a 10g and it's harder to keep stable.
An established freshwater 20 is super easy and maybe 10-15 minutes of work a week (I've timed my water changes) for water changes. If you have city water, you'll just have to decholorinate the water before use with fish, but this isn't work, just dripping some chemical drops in the bucket and letting it sit while you do something else. Though it's important to have your tap water tested (most pet store will do it free) to be safe.
Cats are actually really easy, easier than a lizard. Cats, you just put their food out and a place to poop and they take care of themselves. They have much less to go "wrong" with them like a fishtank or lizard might in the sense that they're fine in a home environment and don't need special adjustments and your air, like the fish's water, isn't suddenly going to kill them (and if it does, you have bigger problems than a cat).
I can say the same about the axolotl, though I check and clean her poops daily.
Lizards are going to be more expensive to set up than a 20 g freshwater, and they can be very expensive on a monthly basis. They also require more daily cleaning. You must monitor their environment and you must have the necessary equipment to do so - not those stick-on dials (which are notorious for being inaccurate). And you really want a front-opening terrarium for lizards and such, not an aquarium with a screen top. So much easier, less likely to accidentally break your expensive lights.
I have a bearded dragon. I just bought $40 of roaches for him. He's old enough that these should last him over a month - but babies can eat $50 a month in just feeders. He has a $30 lightbulb that must be replaced every 6 months that supplies UVB. There are cheaper ones with misleading advertisement that can lead to blindness or Metabolic Bone Disease which leaves your lizard having seizures or a deformed skeleton.
O, and expect to have vet bills for internal parasites with a lizard. They can get them from their food, even if you're careful - and from a big pet store, they're almost certain to have some kind of hitchhiker. Having a fecal float done by the vet is a MUST as lizards tend not to "show" they're sick until it is too late.
Not all lizards require UVB - this is something to research if it's a concern.
If you don't want fish, I would recommend a snake. They eat once a week or less as they get older, and they poop once for every 3-4 feedings or so. You do have to get the temperature and humidity right, and this can be some work depending on where you live - but otherwise very easy. Just make sure to get an "easy" snake like a Ball Python, who is rather docile and whose parameters are easy. Snakes also grow very slowly, but make sure not to choose one that will get too big for you to take care of (my friend has one that will need a 6x2x2' enclosure at adult size).
You'll typically need to keep heat and humidity in parameters. I recommend a dimmable light fixture - makes this very easy to adjust instead of lightbulb changing.
Also, for the cost of a lizard or snake, you could probably get a bare-bones saltwater going and plan on adding something every month or so, especially if you got a tank of Craigslist or the like - my local pet store often has tank + stand for $100 used, and that's a GREAT deal.
