Siddur recommendation list: Favorite, best, and must have siddurim?

I am a collector of all kinds of siddurim, and I wanted to ask all of you what you recommend for my list.

So far I’m up to 16 books, not including my haggadahs/machzorim/etc. My favorite of all of them is my Prayerbook for the Armed Forces from 1958. I personally use the Mishkan T’filah on Shabbos and Gates of Prayer for weekdays. I came from an Orthodox background so I have a love for Artscrolls too.

I want to get a copy of Tehillat Hashem, Birnbaum, Kol Haneshamah, and Union Prayer Sinai Book 2 (Machzor).

So what do you all recommend? What is your family siddur? What is your favorite? Why is it your favorite?