I guess I would have to say the Bridge of Love from the first Valentine's event. Even before we had Royal Restoration instants or Teleport spells that one wasn't going anywhere. Valentine's Day is my wedding anniversary so <3 The Rise of Phoenix was very important to me for a few years. I got it in the first Phoenix event and then a 2nd one in the first FA. The first one I'm pretty sure was the first event prize I spent $ to get. I had one on each side of my castle no matter what until they decided to have it easily available. Oh well! I think Marlo was the next must have & keep. I mentioned that it reminded me of the Turtle in Never Ending Story so my husband said then I should buy it. Didn't have to tell me twice
I think next would be Garden Party. My husband said it reminded him of the beer gardens around Munich. I know it is grapes but I still agree so I will not part with it. Obviously, then the Valentine Float.
It seems that "Most Precious" for me is a bit different than most folks. If I didn't have any of my 'precious' sentimental things in my city then it wouldn't make me happy. I see those things, and a few others, and smile every day