Note: This is entirely informative to help you make the correct descision and is not against or for IF with any bias.
Lets start with the fact that you can access airports worldwide i think in RFS Solo whereas IF has only regions. Secondly aircraft in RFS Solo are severely limited to three short haul ones whereas IF has a good spread. Next, IF has military aircraft, RFS only Civilian. Carrying on from personal experience in network conditions that i can run IF in, RFS has lagged. Next, RFS has built in emergency features which is cool but to be honest we have IFPAX add-on for example and i can’t imagine the majority of people using them more than a few times and also the emergencies are automatically enabled so you could have forgotten to change the settings and crash during a long haul. On top of all this, the aircraft are not very high quality and and the physics is not the best meaning it can be hard to control. In addition, although it has ATC which uses slightly more realistic terminology, it is it quite a basic set up in terms of options and there is no user controllers which is one of my favourite parts of IF.
I’ll add more as i play it a bit more but currently i’d say that IF is the best currently but it is pre-release with more set to be added. I feel that in terms of Solo, i’d rather have regions and a range of aircraft than a 3 and the whole world. Alsoon IF Solo you can make your own FPL on RFS it makes an automatic one. Also i feel that maybe it has either been rushed to grab some of IF’s market or that less resources have been put into it to bring down the price but that has resulted in poor physics and aircraft.
Please also note for now its only on Android.
I’d love to hear other peoples opinions and wouod be happy to try and answer any questions about it.
I am not associated with Rortos or FDS and my view is wholly independant.