I'll disagree with the notion that you don't need a 1/2" ratchet and sockets, and I'd never use a 1/4" ratchet on a 14mm or 15mm nut - use a 3/8" on those, and your hands and body will thank you for it later.
I have a drawer for 1/4" drive stuff (ratchets extensions, sockets), a drawer for 3/8" drive stuff, a drawer for 1/2" drive stuff, a drawer for big tools (air impact wrench, air ratchet, pry bars, mallets and the like). I have 3/8" allen sockets as well as allen wrenches, 3/8" and 1/2" torx sockets, torx and regular screw drivers in another drawer, all sorts of pliers in another drawer. I have strap wrenches and other oil filter wrenches. the point is, I use all of them at some point or another...
I browse the local Harbor Freight store (one is 5 minutes away), and if I see something I might need, I just buy it.