I pick a powerful Steam Machine with lots of RAM and storage, fast CPU, and fast videocard because Steam Machines are basically computers with the Steam OS installed on it. But, I probably install Linux and Windows on another hard drive or hard drive partition, so I can play Windows-only games, and use Desktop programs like word processors, music players, and video players in Windows or Linux.
I think it is not a good idea to get a new console at this time because version 2 of the Xbox One, and the Nintendo NX will be released soon.