My opinion is that it is so dependent on the tractor in question that there is no good way to answer unless there was careful evaluation of both. My best advice is to go for the one that gets you most excited. I think that the differential in cost is immaterial. For instance if you're into the Twenty but are working on the Fifteen because it may be somewhat less costly to restore or vice-versa, you'll always be Jonesin' for the tractor you're not doing. Does that make sense? Then what happens is one of two things: A) you stop what you're on and buy what you desire, or 😎 you finish what you're on and then buy what you desire! If you look at it that way, the cost of restoring what you're not into just went out of sight.
Just my .02. 😊
When I first saw the pics I saw the Rover in the background n thought you were over in OZ Land, lol
I hear what you're saying. I do have a little preference for the Twenty and obviously it also has more historic significance from a model standpoint than the Fifteen. At least nobody has hopped on here to say that one is clearly more difficult/expensive to source parts for than the other.
Part of this equation I'm sure is location as well. I'm in the south central Pennsylvania area. I already have the PV Fifteen in the pictures. In areas of the country where these tractors are more common, it would probably be considered a parts unit due to the number of small parts missing or need to be replaced. But pickings are slim in this area for projects and parts. If I wanted a Twenty it seems like it would require me to drive halfway across the country. Pros and cons I suppose.
Aumann Auctions has a sale ending in Ohio in about a week with several 20's on it it a few configurations.
I understand what You trying to Do, been there doing That .Both are interesting Units Machines ., lets look at it this way, the Twenty is the First Tractor designed and Built the Company that formerly Holt and Best. The twenty is basically a smaller Version of the Thirty that Best produced many parts fit both, [Rollers , tracks less a link front Idlers etc] ,many alterations were made as Time went on ,Particularly Gearbox ,which a cow to work on, , I have had to Get engine Bearing rabbited and crank ground to match and Line Bored [very expensive Operation [, incidentally Engine valves are same as a Twenty Two]. with only 6319 made is Rarer that the PV 15 with about 6500 made. The fifteen is much easier to find parts for as they 'Basically" follow through to the Small Twenty, Twenty two etc. Even though though the Tracks same Measurement right through even to the D2.,and You can still get some l parts from Cat . the worst part of the Fifteen is the Carb, a mongrel to praise it up ! I find it better to work on a couple Units, other wise while waiting for Parts or services to come Good Time is wasted ,Remember that the the Twenty should be Painted Grey and Likewise the Fifteen except for the Last Couple Hundred were Yellow., Good luck with what You decide and Keep us Posted. LJ