Any MSX2 with diskdrive from Yahoo auctions JP will be fine if you just want to play old Japanese games.
If you want to be able to run newer (mostly European) software, you'll need a better one. ;d
I think MSX2 with lot of RAM is sony HB700 , but 220v.
I think MSX2+ panasonic WSX is fine since it is 110v and better svhs video output.
for playing games you can :
- buy cartridges
- get disk games ( by copying disk images if your pc has a floppy disk or buying disk games originals )
- buy an adapter like SD interface or mega flash to emulate disk and roms with images stored in SD card.
but in that last case an MSX2 with 128kb is recomended to have DOS2 .
The far far majority of games/demos/tools runs at 3.58. There's something for 7.16 when it comes down to things like compiling time, settings-scan in Moonblaster, that kind of stuff. But games run fine with 3.58.