Buy an Xbox One and buy PDO.
At the moment that would be the most reliable option with the best display resolution. The console isn't expensive, even brand new the S is much cheaper than the PS4. Used consoles aren't a huge jump in price from the best 360 models. Only bad thing about that is there isn't a huge amount of original Xbox games playable on that console, but there are loads of 360 titles as well.
Of course if you're going to buy PDO physical anyway just get an original Xbox console and mod it. Best compatibility for Xbox games
Modding a 360 isn't as easy as putting CFW on a PS3, or modding a Wii U. The emulation on 360 isn't the greatest anyway, even M$ has admitted that in recent years it was plagued with issues due to hardware limitations.
