What I experienced with the people I know, who adopted:
the most easy for you would be - if the child is as young as possible. Preferably shortly after being born.
There are of course many older children waiting for a real home - but in general they all bring their mental baggage with - so this can be really, really challenging.
There's a special place in my heart for people who choose to adopt older kids. It's not so much mental baggage as it is damage resulting from years of abuse and/or neglect along different axes of the child's life. There's real loss and trauma involved, and there's no way to erase it. The best you can do is help them cope and not take it personally when they lash out at you for what was done to them.
These same traumas exist in some degree even with our children adopted as infants. They each have undergone a sense of loss (to varying degrees, for sure) and have spent time questioning the events that led their birth parents to put them up for adoption.
There's also a lot of loss after the fact because the typically birth mother does not live a very stable life. Our 4 children only have 1 surviving birth mother between them at this point (we think). One has had to deal with the loss of a birth sibling. These kids have a front-row seat to the reality that life is full of pain. We put a lot of effort into teaching them that there is also an abundance of love available to them.
I agree very much. My parents worked as foster parents and I know some people working professional in the area.
(mental baggage was a euphemism)
There is so much going on, people from normal upbringing cannot imagine (and usually do not want to imagine).
Even the children who were not abused in one way or another, how can they develope a stable mind, when they have no stable surroundings?
Dragged around back and forth from instable "parents" to foster parents to various institutions and back. And out again. And then maybe adopted one day.
I would never blame the childs. (I find it also hard to blame their parents, as they usually had a childhood like this, or went down into drugs for one reason or another - always easy to judge from the outside - and they do get judged. Usually at a time when they simply needed help and not judgment - but they don't get help, but their children taken away)
So ... like I said, it can be very, very challenging to adopt a older child. I did not wanted to scare anyone away from it. If anyone feels like this is the right thing for them - do it!
Just don't expect it will be easy.
edit: note, that my experience may be a bit biased through the foster home situation, which is especially hard, because often the parents of the kids often wanted to have their kids back - so this pool is probably the hardest.
But personally I would just want to see the child and see how we feel about it, if there is a emotional connection with the child.
Older children can also be easier, by beeing already very independent. You also might end up being the hotel for a distant teenager. But that also happens with "normal" kids. You never know.
the most easy for you would be - if the child is as young as possible. Preferably shortly after being born.
There are of course many older children waiting for a real home - but in general they all bring their mental baggage with - so this can be really, really challenging.