I have two wonderful children. They have different personalities. And they have had different "issues" as they developed. The older is a great eater, and the younger is a stubborn eater. However, the older is a control freak when it comes to playing, and the younger one is comparatively easy going. But they are both kind, sweet, happy, loving, smart, polite kids.
The fact is, you can't imagine any child being as good as your first until you have your second. You WILL feel the same way about both of them. For me, I have special memories of my first which can't really be replicated because she IS my first. However, I think they are both great.
And on top of it, seeing them together as siblings is a bonus. They give each other a lot of joy. I was an only child too, and I love my children's relationship to each other. I really feel a sibling is a gift to your child. Thier relationship makes them even better!
For me, the second time, with motherly experience, has been so much easier. However, even if you have a difficult infant (colic, etc.) I think you wouldn't ever regret it.
You should never be forced to have a child, of course. But the notion that two is innately more difficult is crazy. So is the idea that you can't possibly be blessed twice with a "good child."