My favorite is a cast iron Singer 201K with a belt driven motor. It's nothing special, but it's in a small table and its a joy to work on it. I have a 99 too, a Bernina 730, a Singer 201K23, an Elna Supermatic, and a Phoenix 283F.
I have an eye out for an early cast iron zigzagger, maybe a Necchi too. I still haven't found a 201-2 with the potted motor. This reminds me, I have a few things to sort out on the Phoenix.