How cruel to make us pick just one!
That se tenant spacewalk pair from '67 shown by Canyoneer and Gwanghoops has always been a favorite. I was already collecting when that came out, but that issue really got me.
When I went in for US airmails in a comprehensive way, I found that Q8 shown by BLCjr exerted a huge attraction despite being in another area. So I forced it into my album.
But I go back to the rich lake color of my avatar stamp, the 1890 #219D, so often. The color is one big reason, but the backstory of that color and then travails of the successor 220 with the caps on twos, 220a and 220c, so I have to say, my favorite is still 219D....

I have developed recently a weakness, though, for the wild exuberance of the eagle and shield of the 1869 pictorial (#121). Give me time and a good auction or two and I might come back and edit my post


- Jonathan