Leos can be very friendly and easy to hold pets. My 13 year old sister takes care of our three girls and they are doing really well. They don't require UVB and you can feed them either crickets or mealworms. they require an under the tank heater at all times because they need belly heat to digest their food. After they are well settled in their tank, they will likely come out during the day (I have three and they rarely hide).
Which reminds me. They need three hides in their tank for each creature (for example: my 30 gal tank has 9 hides total). At least one each on the warm side above the UTH, one each on the cool side, and one each humid hide generally placed in the center or near the warm side. Having enough hides for everybody spreads out and reduces aggression. If you are planning on putting multiple leos together, you will want three or more for the same reasons. That way no one gecko is getting bullied by the other.
Tarantulas are a good choice as well, except they tend to hide most of the time.
Red bellied toads would be great in a 20 gallon as long as you provide a wet area.
Anoles don't really make that great a pet. They get stressed out really easily and need to be misted everyday to get water. Plus the need uvb.
A 29 gal would be nice for one painted turtle.