There is always xplane. IMHO it has a more realistic flight model and the
display is much smoother. Only bad news is that the scenery is poor
compared to MSFS.

http://www.x-plane.com

x-plane is not an option for me. the flight model may be good (don't
know) but it has nothing to offer in terms of system simulation in
airliners. those jets don't even have APUs...