Hello, we have had both guinea pigs, other small furries and caged birds (cockatiels and budgies) in the past. Pros of birds compared to furry things are:
-No smelly bedding for the cage, just a lining paper which you pull out and replace regularly.
-No hay or shavings/paper bedding to get kicked out of the cage and strewn around the place and clog up the hoover.
-They are smart, fun little birds and more interactive than an guinea
pig or hamster if tame and friendly, they can be taught to whistle on command, do a loopdy loop or other simple 'tricks'. They aren't as food motivated as guineas but can bond well with humans if socialised well from a young age, some are happy to be carried around sitting on your shoulder all day and one of mine used to perch on my laptop all day while I worked which was pretty cute! It does seem personality dependent though as some were very stand offish and never really liked people, only other bird company, which would be disappointing for your DC if that was the case.
-Pretty to look at.
-Can be longer lived than the guineas so less upset to deal with there, but ours had a habit of literally falling off their perch and dying one day with no warning and for no apparent reason 
Cons of the birds are:
-Space - they do need a large indoor cage, much bigger than the traditional 'budgie cages' you see which are really only big enough to sleep in. I know guineas need a lot of space too but at least you can move them outside in the summer.
-Noise! Budgies make almost constant low level noise, if they aren't whistling or 'talking' they are noisily crunching through seeds or flapping around the place. Cockatiels don't whistle/chunter as much but they do a ear splitting screech pretty regularly for no apparent reason... it used to drive me mad TBH especially if trying to work from home and take calls which would be regularly interrupted by loud screaming 
. Our cockatiels which were rescues used to suffer from a weird kind of night terror too where they woke up in the middle of the night screaming and banging around their (covered, dark) cage which was quite alarming/distressing, that shouldn't be a problem with non-troubled birds though!
-Poo! We let ours out to fly around quite regularly as IMO it's not fair to keep them caged up all day, but they will then poo anywhere they land, and its sticky and unhygienic poo so you need to follow them round with a wipe and spray. People do say they have toilet trained their birds but I have no idea how, ours were not receptive to the idea 
. Also although the main cleaning is to change their cage lining, ours would poo on the bars and door as well and this was a fairly grim job every so often to clean it all off.
-Chewing - they love to chew and sharpen their beaks, you need to provide them plenty of toys to do this, they will also spit seed husks everywhere which do need sweeping up. When out of their cage you need to be vigilant for them chewing furniture, possessions or fingers! Ours destroyed a custom made venetian blind when not adequately supervised and also numerous books, picture frames etc by chewing.
-Escape - birds on a par only with hamsters here for being escape artists and the subsequent frantic hunt and distressed children - you think it's obvious how to prevent it but every regular bird owner I know has lost at least one through a carelessly left open door or window and it is stressful as all hell. We lost one when a DC decided it would be nice to take his cage out into the garden one day and the bird managed to bang against the door and open it, he flew away and was never seen again which was very upsetting for the poor child. Guineas much better for this I find, too slow moving and fond of their home to escape!
We now no longer have birds, overall I found the cons outweighed the pros and though I did like them, I find the guineas lower maintenance and sweeter. Budgies can live a long time, up to 10 years, so it is a big commitment, any way you could 'borrow' one for a while to see how it goes?