I don't know anything about those FAA parts (I'm EASA regulated ), and "study level" can really mean anything and nothing. I mean, as an example, is it important to simulate fuel sampling and oil quantity checks on a small piston aircraft, 'cause that's what pilots have to do in reality? Or is your focus on flight dynamics and avionics? Where to draw the line? I went with a selection of aircraft that I consider "study level" because they require studying how the real thing works, and are also built in a somewhat instructive way. I would never consider a model "study level" if it doesn't come with documentation (or documentation is otherwise publicly available) - how should I study if I can't find the required documents (POH, FCOM, FCTM, ...)?
I'm trying to match your set of categories with my favorites:
Small aircraft for private pilots and flight schools:
The AirFoilLabs Cessna 172 NG makes an excellent model for flight students - though I'm still waiting for the analog panel they announced
The Torquesim Cirrus SR22 is IMO the best high power piston aircraft model out there - particularly the version with Entegra avionics is superb. Personally, I prefer the TN over the normally aspirated engine, since managing a TN engine correctly (which TS models pretty accurately) IMO is a great experience and additional stuff to learn.
Light twins (multi-engine trainers and hobbyists):
IMO not covered. There's a load of excellent models out there (Aerobask's DA62, Torquesim's Islander), but I wouldn't categorize them as study level.
Medium sized aircraft for charter ops or corporate transport:
The TOGA Mitsubishi Mu-2B Marquise (v2) is my favorite turboprop - it's a quirky beast, so IMO a lot more interesting than the "boring" TBM (though that's an excellent aircraft model as well, just not as exciting as the Moo). You can learn a bunch about roll control and roll trim flying this aircraft, and it will savagely punish pilots flying uncoordinated turns.
Light business jets
IMO not covered yet by something deserving the term "study level". I suppose TS will change that with their Citation II, but it's not available yet
Heavy business jets
HotStart Challenger 650, no doubt. It might get a strong contender with the upcoming Aerobask Falcon 8x, but absolutely not sure there.
Airliners
IMO none atm. Many models out there get certain aspects right, but I don't see a model that actually integrates all aspects properly. As a compromise, I'll list my favorite airliners which I consider close to study level:
Regional: FlyJSim Dash-8 Q400
Domestic: ToLISS Airbus A321
Twin Aisle: iniSimulations Airbus A300
Intercontinental: Felis Boeing 747-200