The first plane I owned was a '46 Cessna 140, which sat squarely at the intersection of being the most beautiful plane and what a 22 year old brand-new pilot could afford. There is something inexplicably appealing about mid-century taildraggers. Maybe it is the static nose-high attitude that makes it look ever-ready to leap into the sky even while chocked on the ramp. I think that has been said before.
As you know the 120 and 140 are structurally identical, except for wing flaps, and differ mostly in options. Mine being the 140, it had simple manually-operated plain flaps which were minimally effective but useful nonetheless; and the rear window, though many 120s now have as well. The 140s when new also came with an electrical system, but I'd imagine most 120s still flying have had this added too. Mine also had the metal wing STC applied long before my ownership, replacing all of the factory fabric wing covering with aluminum. The O-200 conversion was also a nice-to-have with the small boost in power helping both in utility and safety.
In terms of the economy-to-fun ratio, I don't think you will find a better value airplane that is as fun and enjoyable to fly. (My E-series Bonanza is a close second, but definitely a step up both in terms of the operating budget and complexity.) I've flown my 140 all up and down the east coast and to all manner of small airstrips, airplane-friendly golf courses, and of course nothing precludes landing at large airports as well.
There are many outstanding examples of 140s out there that have received lots of love by their owners. If I were ever to find myself without a plane and the opportunity presented itself, I'd snap it up in a heartbeat and fly the wheelpants off it.
