TSO, you make a lot of sense. While we all want the "best" tractor for the "least" cost, buying a tractor is all about compromises - just like a lot of other things. Here are my requirements:
Absolutes:
1. Cab with a/c
2. Loader with SSQA
3. 4wd
4. 35 PTO hp minimum (40 would be better)
5. Good dealer (if buying new).
6. Established reputable brand (no chinese tractors or off brands). I don't consider LS, Kioti, Mahindra to be "off brands".
I have a very strong preference for HST. But for a screaming deal on the right tractor, I'd consider a hydro shuttle but not a regular shuttle.
I'd also prefer a Tier 3 over a Tier 4, but it's not a deal killer. I didn't list remotes, 3rd function, etc. because I can add all that. And I didn't list build quality because all the brands I would consider are good quality tractors.
I'm 60 years old and there's a decent chance this could be my last tractor. (Famous last words.) So buying what I want/need carries more weight than saving a few bucks and making too many compromises.
But that doesn't mean I want to be stupid with my money. Using your example of the HST+, at $500 it would be a no brainer. At $5,000, it would be a "no deal." My limit would probably be the $1,500 you mentioned.
Sorry to be so windy.