Is any age easy?

I have been thinking about my friend AJ's recent post on her blog. She was discussing how her four year old has been frustrating her lately. As I thought about it all night--during which Ryan and I had a blow out fight--I wondered, is any age easy? Is it the age or the person behind the age?

Ryan: age 8 (will be 9 in December)--He is not someone I consider to be an easy child. He is volatile so you never really know what you will get out of him. Much of the time he is kind, considerate, an excellent helper to me, and very well behaved at school. He gets up in the morning and gets dressed, makes his breakfast (and sometimes his sisters' as well), and doesn't dawdle. In activities/sports, he puts 100% into what he is doing. He has been blessed with the gift of modesty, and is not a whiner at all (thank god). Losing doesn't really affect him much either. He has tons of amazing qualities!
When he goes off though, watch out. I won't even give you details about last night, because it would be broadcasting that I can't control my kid. To his credit, he exploded, called me some names, but when he calmed down he apologized.
Verdict: not easy

Kate: age 6--Kate is 'easy' in all the ways Ryan is not. She is very kind hearted, good natured, friendly, and just a darling. She goes to bed easily, sleeps find during the night, and when she wakes up, she doesn't wake the house up (like Ryan would). She will tell me I am pretty, she loves me, and covers me with kisses and treats me very well.
On the other hand, she spends WAY too much time getting dressed each day. Most days her outfit is a bit absurd so we argue about that. She takes forever to get her hair & teeth brushed, and if she is drinking her vitamin/juice cocktail it takes up to 45 minutes. No joke on that one. Lately she argues about everything, "No, I don't want to, why do I have to?" When she doesn't get her way, we hear, "This is the worst day EVER." She is my whiner, does not stand up for herself, and the latest concern is her lack of drive for anything. She is in gymnastics right now. She is a solid little piece of muscle, but does she try hard? Eh....She isn't one to put in her fullest into things. It's not a big deal really, but it is difficult to deal with when you are used to the other child being such a hard worker. It's not just sports either. It's reading, writing, etc.
Verdict: easy in many ways, but drives me crazy in others

Olivia: age 3--Olivia is demanding, bossy, funny, LOUD, etc. She does not back down easily (Like her brother), so any fight takes a l-o-n-g time to settle. She is strong willed so I can only imagine that she will get more difficult.
Verdict: easier because she is my third child, but is becoming a difficult little pistol

Here is what I want to know: how does that lady with 18 kids do it? I bet hers are well behaved........