This isn't going to convince a republican. In fact I wouldn't try to convince a republican as, and I've said this before, I'm mostly convinced by the more rational republican arguments. My love of the monarchy is wholly irrational.
But I wanted to say a little something about what I think is the best quality of Her Majesty; that is that she embodies our better qualities.
In the world of Second Life, users create avatars for themselves based, usually, not on what they actually look or act like but as they would wish to be. They use these avatars as their "front" to meet others, to interact and explore.
Her Majesty is the avatar of the United Kingdom. She is compelled by protocol and tradition to represent the better qualities of our nation. She, and her forebears, are stoic when faced with disaster. Polite and courteous no matter the situation. Strong yet not aggressive. Humble (in manner if not in more material matters) yet not grovelling. We send Her Majesty as our avatar to other countries to put our best foot forward and use her to greet the good and the great who visit us.
No greater example of this can there be than in the events surrounding the death of the Princess of Wales. When our country mourned (I won't get into my feelings on those events!), we forced her to adapt to our requirements, to grieve a little more publicly than she would have liked to personally. She is not a free agent, but is the beating heart of our country.
Of course this is not a surprise, at her coronation she swore to serve our country. Her office is not of ruler but as a representative of something larger than her and than us all, of something a politician can't embody for more than a short time. She is our history and our nations soul given a body and allowed to walk among us.
That, I believe, is why Her Majesty is so special, for she has taken these duties upon herself with never a public complaint or an urge to stamp her own personal beliefs upon the institution. And it's also why it's always sad to see people try and bring her into political matters.
For 60 years she has served us, and served us well. I wish her many more years on the throne!!
If you feel benevolent and particularly generous, this writer always appreciates things bought for him from his wishlist