Pretty much all I used to fly was the TDFI 717 and the Majestic Dash 8. There was just something satisfying about these planes… more interactive, less cerebral than the PDMG stuff, but still could Go Places in a way that a GA plane doesn’t.
If anyone out there knows what I mean… what do you fly now?
the 717 may be replacable by its older self, the Leonardo MD80 series. Both are DC9 essentially. It’s older though, less MD11 like.
The Q400 is probably not really replacable atm. If you want to fly a pretty good twin turboprop anyway the Blacksquare Kingair is really a good addon, although quite expensive for what it is. But together with Milviz’ PC6 it’s probably the best turboprop available. It has PT-6 engines, that’s what the sim itself simulates anyway.
Closest on the Dash 8 would be the Asobo ATR, good and cheap but quite up with the majestic q400 unfortunately. It is silly cheap thought for what it is and worth a go IMO. The Q400 is the aircraft I miss most from P3D. There’s a Dash-7 in development right now but no Dash 8’s as far as I know.
If you want a t-tail that requires thought to fly, check out the JustFlight F28, it’s amazing.
The Justflight F-28 is great airplane that can get into a lot of the same places the Dash-8 and the 717 can go.
However, it is a product of the 60’s so you will not have the automation that you are used to, but it is a very nice change of pace.
More interactive and less cerebral than PMDG?
This sounds awesome, but what does it mean?
No sorry your favorite planes have not yet arrived on FS2020, but there is hope…
And TFDi Designs still makes no move bringing their 717 to FS2020:
https://tfdidesign.com/717.php
Sorry but the future looks very grim and hopeless. Just like my favorite the 747 Queen of the Skies… I will probably NEVER see for next-generation flight sims 
Oh and I fly the Fenix Airbus. Perfect photorealistic ultra high polygon and super high definition textures cockpit, superb system realism.
Give it a try and you won´t be disappointed 
I heard a while back that PMGD will be working on a 747 might be a while though.
Ah, I love those two… Unforrunately, I am on P3D v6 with no plans to go back to 5.4, so the Q400 is the ONLY third party aircraft officially offered for that sim, so that’s where it is now! It will eventually come to MSFS, but for now the ATR seems to be the closest, followed by CRJ from Aerosoft (basically the jet version of it, but with a very similar cockpit layout, though the FMC is entirely Boeing-like)…
The 717 is unique and there is no alternative but the excellent Leonardo Maddog is your answer. Believe it or not, I’d suggest FlightSim Studios’ EMB-170 and 175 as something closer to the Boeing 717. They aren’t as high fidelity YET, but the guys are making good progress in development.
Q: What can replace my fav P3d aircraft (717 and Dash 8)
A: ANYTHING you want with M3 ( free Model Matching for Microsoft Flight Simulator.)
“We have the little ducker in sight”
