A pilot friend who was captain in MD-11 told me “IF it aint Boeing, I aint Going” because then, they were the best. Personally, do not like Airbus anything so cannot respond to those, just will not fly them.
Boeing PMDG 737-Any Model is excellent; however, it is as close to real thing as you can get in Real Airliner, you can turn off “failures and maintenance” items. If you get it, the 900 is coming out within month or so, if having latest, then wait for that. Read the introduction and follow steps for the Tutorial Flight in root folder if purchase. Rumor mill at PMDG Forums are/is, the EFB will arrive close to if not at 900’s release. If you want to learn more, find and subscribe to that forum, and watch the Videos on YT for those. They will update planes/systems/EFB over time, so even at release it will not be complete.
The 747 in game now is good and will teach you lots of stuff which will carry over to the PMDG models, and also work in the 787 (I personally do not like). I think the FMS in sim 747 and PMDG planes are the same, have not flown 747 in while. I posted a cold and dark CL for the 747 last year which will work for you. It’s not in tutorials, as could not get it in there. I have in sim flown all of them extensively, personally the 747 in game and the PMDG 737-700 BDSF are my favorites CA’s.
The C-17 (DC Designs Q3-2023) I will get and then mostly fly that one as have lots of time in FSX and XP for that plane, it loves to fly, has long legs, and hauls lots of stuff. Many nations fly that plane as well, so will have lots of liveries once released.