LED T8 tubes: plug-and-play or direct-wire?
Direct wire.    Worst case you have to change a lampholder.   

Plug-n-play doesn't allow a ballast, it requires a ballast!  And of a specific type - if the fixture has the wrong type, you would have the ignominious task of buying a new ballast and also possibly change lampholders too.  It's one more thing to maintain.