6th gen was the last good gen and if you have them modded you're set for life.
Slim PS3 with CFW covers PS1,2 and 3 games, can be over locked, still free online, and you can download games directly on it with PKGi. Install an SSD to improve load times, cut down on heat and make the XMB very snappy

An RGH modded Xbox 360 also covers OG Xbox games with vastly improved compatibly. You'll also be able to obtain whatever content you desire from the now defunct Xbox live arcade/store. An SSD will also improve load times and temps here

A modded Wii gives you access to every GC,Wii and Wiiware title. With emulators for every 2D console and the ability to output 240p, the Wii becomes a cheap retro powerhouse when coupled with a CRT.