Im glad you got the PS3 working, hopefully it lasts for a long time to come.
If you managed to find a PS4 on older firmware then its possible to hack it. To date the Xbox One hasn't been hacked, however you can unlock a dev mode which does have a few homebrew applications you can download. These don't get access to the full power of the Xbox One though.
I'd honestly recommend the console which has the games on you wish to play. Both have been a bit disappointing this generation I personally think, of the two i'd get the Xbox One.
I have however enjoyed a lot more games on the Nintendo Switch, that is rapidly becoming my favourite console this generation.