[kevingross]

It all depends on what you plan to do with them, what needs you have. If you're just changing wheels occasionally, a decent quality 1/2" drive is where to begin. If you're getting into more serious maintenance and repair, a 3/8" drive will be needed (and should serve you just fine for spark plugs). You really won't need a 1/4" drive wrench unless you get into some fairly specific work needing accuracy with small torque values.

I do race prep/service/reman of transmissions and own more torque wrenches than any sane person should, from 1/4" through 3/4" drive click style as well as wand style and the funky gauge unit you see in the workshop manuals for measuring bearing preload. They all have their uses in my niche. Almost all come from Snap-on and I get Nm rather than ft-lb graduation because that's the world I live in.