First off, congrats on being a soon-to-be first time pet owner!
I have always grown up with pets and know a decent amount about different species, so hopefully I can help a little bit.
Dogs are great pets, and there are so many breeds to choose from to pick one that would match you. I highly recommend doing a lot of research on dog behaviour and training before you get one. Proper training for both you and your dog make both of your lives so much more fulfilling. Always do your research before getting any breed, and make sure you either adopt or buy from a reputable breeder, stay away from shops, craigslist breeders, etc.
Now, I have never owned a ferret, so I can only say what I have heard, but from my understanding they are very high energy, and they smell something awful. They are smart and very affectionate, but I believe they require a lot more care then it seems.
Chameleons, or really any beginner reptile for that matter, make great pets because they are easy to care for as long as you understand their specific needs. They aren't as 'companionable' as say a dog or a cat would be, but I find my snake very calming and good for my depression. He doesn't require a lot of care, and its surprisingly therapeutic to hold him and watch him move around. Just know that the initial setup cost can be quite a lot depending on what you get. Again, avoid shops, see if your area hosts any reptile expos and check them out, talk to the people, hold some animals. From my experience, breeders love to share their knowledge to a new reptile owner who is eager to learn. I also find the prices a lot cheaper (unless say, you buy a $6k rare morph). My snake was only $45 when I got him, is extremely healthy (unlike all the petsmart pets I have gotten), and I can always contact the breeder if I have questions.
As for birds, they are super companionable and talkative, but can be to a fault. They tend to get attached and sometimes even defensive of their owner, and if they become stressed they can pluck their feathers. My mother had a parrot who would bite her and other people if they got too close. They also poop a lot lol. I do love birds though, they are absolutely brilliant and fun to hang out with. I have two friends who own birds, smart little guys, one loves to dance when his dad plays music. They are trained to poop every 15 min in a tray. One isn't a fan of new people, however, and likes to bite ears haha.
Also, please don't think that just because I put a lot of downsides in there that it means any of these don't make wonderful pets. I just assume you know more about the positives since they were the ones you were considering and it is always good to have a perspective.
I don't know how severe your friends allergies are, but there are some 'hypoallergenic' cats. As far as I know, no cats are 100% hypoallergenic, but there are a few breeds to choose from.
Rats could be another option, they are very smart and friendly, almost like mini dogs, and you can even train them. They poop a lot, too, though...and can be a bit stinky, haha.
Honestly, though, any animal can make a great friend as long as you are willing to put the time and energy into researching, training, and care. Before I was very active, I got a Husky knowing that, with my personality, I would change my behaviour to make my dog happy, and it has worked very well. My sister, on the other hand...probably shouldn't get a husky lol. Just be honest about your capabilities!
If you have any questions, particularly about dogs, cats, and reptiles, feel free to shoot me a message. I love animals and would be happy to help you figure out whats best for you ^_^
I hope any of this made sense, I can't sleep so I decided to lurk the forums.