I guess it all boils down to individual taste and what overall look you wish to achieve in your livingroom.
Personally, I like to have only one type of wood in a room, too many types of wood can be overpowering and tiresome after a while. I think oak would clash with your maple floors, they're similar woods in overall colour but they have different hues.
Walnut might be a nice contrast to your maple floors providing it's a dark walnut to contrast with your lighter floors.
However, off white/ivory painted units get my vote......a nice, modern airy look!
Try to get some samples/off cuts of each choice of wood to see what looks well with your floor and take your time with deciding.