This my story too....I have 20+, 18 or 19 are turn key, and a dozen or so are in a rotation to be near the door when duty calls. I love to burn petro through all of them, whenever I can come up with an excuse to do so.
My favorite tractor is my Bolens 1050. It's my favorite because it's reliable and has never let me down. It can sit for 6 months without being run and still fire right up with no problems, it's also a beast of a tractor and can do a lot considering it's only 10hp.
I don't have a set go to tractor. Normally if I need a tractor I'll go to the shed and take out the one closest to the door, depending on what task I need done. Also most times I only have 3-4 tractors out of 10+ that are turn key and ready to go.
My go-to is my Allis B-110. My first, and best IMO. Its short wheelbase, 10hp Briggs, hydrolift and gear drive makes it a real mule for anything. It has that "patina" mentioned earlier that makes my garage queens drool.
I have found great utility from my late model tractors, but they dont give the same simplistic feel of the old Allis. She still gets called up for 1st string snow team duty!