Take it from me. I own a zoo at my house and here is the breakdown of what I got.
5 Cockatiels
1 Quaker Parrot
1 Eclectus Parrot (had 2 but donated one to Local Vet)
6 Hermits (land)
1 Betta Fish
1 baby zebra danio (the only one to survive)
about 20 baby sailfin mollies
10 gal. fresh water tank with fish
20 gal. salt water tank with LR and fish
I have also owned......
Hampsters
Rats
Snakes
Gerbils
Dwarf hampsters
dogs
cats
ferret
Here is my outlook on all of these.
Cockatiels: Messy, loud, friendly, nice to look at, can play with to some extent. Expensive. Can live up to 15 to 30 years.
Quaker Parrot: Do lots of reading on these before hand. They will run your house and life. Fun. can take walks with you (if wings are clipped). Very loud. Comical. Can talk. Does not play well with other birds (very dominant). Read, read, read. Expensive. Can live up to 15 to 30 years.
Eclectus Parrot: Very colorful birds. Can talk very well. Tend to only bond with male or female (person). Lots of care (diet, beak trimmings, nail trimmings), expensive (large cages, food). Can live up to 20 to 40 years.
Hermits (land): Fun to look at but not much fun in the handling department. Quite boring. Spend most of their time hiding in their shells. Low cost.
Betta Fish: Very easy fish to take care of. Colorful.
fresh water tank with fish: Your on this site so this should be familure to you.
salt water tank: Ditto from above.
Hampsters: Can play with, fun to watch, comical, smelly if cage not kept clean, can bite, relativly low cost in supplies and care.
Rats: One of the most smartest rodents. Playful. Can train to do tricks and in some cases potty train. Tails DO NOT feel slimy, there dry like skin with no hair. IMO, very nice pets. Cages smell if not cleaned regularly. Low cost.
Snakes: Depending on what kind, very nice pets. Stick with BOA's (i.e. red tail, columbian) or Pythons (i.e. Pall python). Hardly any cage smell. Cage cleanings about twice a month. Low cost in feeding (they only eat about once per month (summers) and about once every other month (winters)). Can hold. Can take outside and let roam your yard (check them over for ticks or mites when done). Eats live foods (i.e. mice, rats, rabbits (if larger snake)).
Gerbils: THEY BITE. NASTY LITTLE S.O.B.'s. Otherwise same as hampsters or rats.
Dwarf hampsters: Same as hampsters and rats.
dogs: You have them so you already know these.
cats: Cute, cuddly, not as entertaining as dogs. Boring. Will not do tricks, fetch paper or shoes and will not get that beer out of the fridge for you. Can be expensive depending on the type of foods and vet care.
ferret: Very entertaining. Mischief. Get into anything. If head can fit in it their bodys will to. Can hold, play games with. Basically, just like having a little puppy all the time that gets into mischief. Can open your cuboard doors. Some odor even after desenting (not much). Cages smell if not clean often. Can take for walk (with proper lease/harness). Can be costly (cages, toys, etc.). Must have lots of things to play with or they will find things you don't want them to play with. Very fun.
Hope that helps your question. Sorry for the long post.