the only one out of these I do have is a cockatiel, while I personally never really liked smaller birds this little fella, and the budgie kind of grew on me while I had them in my care for replacement, hence the adoption of them, well that and the combination of them beeing of considerable age so hard to find homes for).Anyways neither of them is really less bird than my amazon, although I got to admit I probably spend more time with the amazon but thats more so becouse he is seeking the attention while the other two are contempt following me around when their out since their not really tame yet and doesnt really trust me that much, they occationally come land on my shoulder and more often than not steps up, but these are birds that has been caged for a looong time and never really socialized, so I am expecting things to go slightly slower than with my young amazon.
Now since you asked about the cockatiel, I find them naturally curious, most birds are but for some reason cockatiels seems more curious than most, even my one that doesnt allow any touching etc yet still has the need to be nearby, if I'm watching TV he sits on a wallmounted perch next to the sofa(sometimes on the back of it). On the other hand i've always thought their cute, although never thought of em to be birds for me, simply becouse of their small size, im a big fella and am afraid ill crush that little thing

. About dusty, yeah they do dust some, but regular vacuuming is good over here atleast, if youre gonan keep a flock of them you might want to add an aircleaner, but that goes for most birds really. I havn't really looked into the lifespan of the other two alternatives you posted, however I do consider their lifespan long enough to never be seen as beginner birds, mostly becouse im not really to fond of that term... since it somewhat implies that it is a bird you would get to get used to having a bird around and then replace it. However it is a quite easy bird to handle, the bites, if youre bit, is not that bad. their quite social, kind of like a miniature cockatoo, well thats basically what they are. The social bit also means they quite easily gets boored if your not around alot, also true for most birds tho.
I've found mine quite easy to train, as long as it requires no touching. but wave, turn around,target and step up was aquired within a few days, millet spray works wonders...
I dont know really, the choice of a bird has a lot to do with the specific owner, and if you consider a cockatiel to be too ugly to look at I would never recomend you to get one. However for a bird of that size I consider them a really pleasent bird to have around. Then again nothing beats the feeling of love at first sight... preferebly by the bird tho, atleast if your looking at already tamed/hand raised/adoptions etc. if a bird really likes you chances are you will like that bird instantly as well. So I'd recomend you to go visit birds you actually can interact with somewhere (if there is such a place you can visit).