With over 80 machines in my herd it's hard to pick just one. Usually my favorite machine is the one I'm using at the time as long as it's behaving. I use modern machines too, not just vintage so there's that.
My long arm, I love that machine.
Of my 5 embroidery machines the Janome 500 is probably the favorite, although the rest have spot as a favorite for different reasons. The Janome 200e was my first. The Janome 350e has the free arm so it's useful. The Brothers(PE200 Snoopy machine and PE400D Winnie The Pooh machine) are sentimental favs.
I'm not technically a Singer gal but my 201-2 was my first and is absolutely my favorite Singer machine. There's just nothing like that smooth feel. The 301s run a close second.
Out of all my Brother machines(pushing 40 of them)there's a few favorites. The '56 and '57 Pacesetters. My Moms '64 Prestige. Technically it's not mine any more, it belongs to my oldest but it's still in my heart. The toy Baby Brothers are so cute. The metallic mauve and cream Riviera is the prettiest. The pink Selectomatic was my best garage sale find. The '76 B200 is my only hand crank. I could go on and on until I've listed most of them. That's why I say that my favorite is usually whatever I'm using at the moment.
Cari