I've been thinking about it, and I've decided this: the royal engagement outfit has to be one of the hardest outfits in royal life to get just right.
First of all, it's not an everyday business meeting. (Well, I suppose once upon a time it was a business meeting, but I should hope we've moved past that by now.)
Now, I love me some Tatiana, but her engagement outfit just wasn't...special, you know? And even when you fancy the day-to-day suit up, à la Letizia, you're not immune to criticism.
Second, it may not be an every day event, but it's still not an evening occasion - Sophie's engagement suit I recall being criticized as too "evening" just because she went for a little beading. And there's something off about Charlene in a long dress next to Albert in a regular old suit.
That said, it's not a casual occasion either, Mathilde. (I guess they were going for the young and fresh angle?)
Thirdly, one must be careful not to date oneself.
Because as these two ladies well know, the engagement photos will remain long after the marriage ceases to exist.
Yes, timeless is the way to go. Princess Elizabeth looks well-dressed even 60 years later.
And at least Madeleine can be proud of her engagement outfit, even if she didn't end up being proud of the engagement.
Now, let us revisit the case of Miss Catherine Middleton:
Another one for the timeless category, I say. Not too fancy, not too casual. Made by a British designer (Issa, a fave of Kate's as well as Beatrice and Eugenie). Hits it on all points, all while managing to avoid too great a comparison to the inevitable:
Tell me: who tops your all-time best dressed royal fiancée list, and where does Kate rank on your list?