I’m not too sure if I could really answer ‘yes’ or not - a number of Key’s visual novels mean a great deal to me for a number of reasons, and they’re certainly up there in my favorites. I’d definitely say that Little Busters! is the visual novel I’ve enjoyed playing most in several years now, and I’ve become incredibly fond of it and deep into it in a way not many visual novels (or works of fiction full-stop) have got me.
One of the reasons I admire LB! is for the things it does with the VN medium itself - those who have played it will know what I mean. On a similar line of thought, I would probably place Uchikoshi Kotaru’s works near the top of my list (those that I’ve played, that is - Ever 17, 999, and Virtue’s Last Reward). I feel like Ever 17 especially is a VN that could only really work as a VN, due to particular elements of its plot. It takes advantage of the medium in a way that really blew my mind when I first played through.
(The one downside of Uchikoshi’s works is that while his twists and turns are really good, he does tend to reuse themes a lot - I feel like Ever 17 went in-depth to a series of ideas whereas 999 presented them in a clear and stylish manner, and by the time I got to VLR it was like ‘ah, this is similar to Ever 17 when…’. Meanwhile my friend played VLR first and had a similar but differently-ordered reaction. I think with Uchikoshi, the first game of his you play in that series will probably have the most impact.)
So the experience of playing Ever 17 and 999 was amazing in a “this is a thing that only a videogame can do” sort of a way, and I found them breathtaking. That said, I’m nowhere near as attached to the storyline or characters as I am, say, LB!, so it’s kind of… the topic says ‘favorite’ so maybe I would say that LB! is my favorite after all? It’s hard to say, really. Ever 17, 999 and LB! would be my top three, I think.