Regional- E-170 & E-175
The E170STD has pretty decent runway length so I can take it most everywhere! I usually keep it as a sub fleet given that the 175 is more economical. The difference is minimal but given that the overhead cost isn't affected I usually keep the bulk of regional fleet filled with the E-Jet fleet
I don't like to do anything smaller. Partly because I personally HATE the CRJ family and because the ERJ-145 Family (and other 50 seat jets) just doesn't have the economics for me to care enough about them.
Short/Medium haul- Airbus A320 Family
A318- Its sort of an underrated plane! I adore it! This is partly due to the fact that I often make GRR a HUB for my airlines so its usefulness in that small city is unrivaled. Its also fills the gap between fleets beautifully!
A319/A320- When its said and done these sisters are true workhorses. I usually pick one to stick to since they are so similar. I like the 320 a little more but it also kind of depends on what's going on and where my bases are!
A319LR- I LOVE this plane for small transatlantic! especially out of my GRR base!
A321- I ADORE the 321! I use a legacy configuration! so 5-24-179 and its the perfect sweet spot of flexibility and profitability! I can use it on ORD-KEF or DUB or I can use it on ORD-DTW and it'll still just absolutely rake in the money for me!! Its NEO sister is even better!
I think the 737 Family is great! typically I order them as well because I want to get as many planes as fast as possible to open as many new routes but in the sandbox world I stick to only one aircraft family!
Medium haul- BOEING 757 FAMILY
757-200- In real life this plane is known as the plane that can do everything! This aircraft family even ages like a fine wine <3 if I operate both the 321 & 757 families ill typically have a subfleet of 752's that I use for South America & Europe
757-300 THIS PLANE IS LITERAL GOLD!!!!! This plane is my domestic and medium haul workhorse! This plane in real life was very underrated (it came out right before 9/11 so it never really had the chance it deserved!) Currently UA & DL operate the snot out of this plane! Its just such a workhorse! widebody economics for narrowbody costs. This plane does not have a direct replacement. That's usually what I struggle with. Good news is these games end at 2030 at the latest so no love lost if they stick around till the end of the game
Medium/Long I usually use both the A330-300 and the 767-300ER. They're both great planes! I have to say that the 767 edges out the A330 in the sense that I can put the 67 on more routes due to its smaller capacity! that makes it alot more flexible!
Long haul. ALWAYS ALWAYS ALWAYS the 777 and 787 Families!!!!!!
777- I love a subfleet of the -200 for medium haul actually! so that makes the family fairly flexible! I ADORE the 200LR and the 300ER!!! both great airplanes! 200ER is great too!
787- That aircraft Family is known for its economics so you cant go wrong there! I cant say I use the A350 so I don't know enough about how it competes.
747D- I use them on HUB to HUB and transatlantic to LHR & FRA great plane if you can fill it! plus you can mix the fleet with the -400ER and -8i so it has some economics too it!
A380- freaking BEAST!!! A lot of money coming in if you can fill those seats! if not then its a thorn in your side! you gotta be aggressive in making sure your competitors don't outprice you!
Q-200- hardly uses any runway. but i can only think of maybe 5 or so cities that only it can go that even my E-170's cannot.
A330NEO- I know that its a good plane but I just haven't found the perfect fit for it yet!
Hope you can chew on that info!