I have not encountered very many different ages and temperaments of children yet. At least, not in children of my own. But I have to say, the age right around one (say ten to fifteen months) seems like the most difficult so far.
There's no denying that it's also the most adorable. All the chubby baby cuteness is still intact, combined with all the curiosity of a toddler and the occasional attempt at communication in some entirely unique dialect. D2 will copy D1's inflection perfectly, sitting around muttering undecipherable questions to himself ending in "esss" or "oooo."
But at the same time, they stop taking all those lovely extra naps they used to need, but they're still too small for those handy activity ideas to keep your toddler busy. You can't leave them alone for a second with anything smaller than their head, because they will eat it, or larger than their head, because they will use it to climb onto the piano.
Besides, the only activity that really interests them is learning to move, and for that they want your constant assistance: if your fingers aren't available, they'll wrap around your legs. Forget taking a shower being a luxury; ANY trip to the bathroom is a luxury.
Then of course there's that little problem of Original Sin, which is beginning to poke its head out, so cleverly mixed with innocent babyishness that you never know quite what to do. Just the time you're sure it's a temper tantrum, it turns out to be a howl of anguish--just the time you're sure it's a real problem you see that little, "I got you!" look in their eyes. Whatever you do, you're bound to get it wrong.
But it doesn't matter, because they're stuck with you. And they don't care how evil of a Mommy you are. They still want you.