I used 1/2" drive for years (good quality set) and never had too many problems but then I bought a 3/8" drive set about three or four years ago and it was a revelation; easier to use for most stuff - they were medium price so will probably need another set in the next couple of years; will buy a good set then and hopefully one of my kids will inherit them (but none interested in cars/mechanical/fixing stuff as yet/maybe never)
I would say 3/8" drive for most things with 1/2" useful (better?) on suspension, brakes and the big stuff (subframe towers, crank bolts, diff, etc) where I would use 1/2" drive or 3/4" drive if you have them but 3/4" stuff is seriously expensive and I just couldn't justify getting it for the few sizes I needed so I bought a few large 1/2" drive loose sockets to go with my set. (might be just me but the cheap 3/4" drive sets look really cheap and nasty and the good ones are pretty expensive)
As Ethel mentioned cheapy 1/4" drive sets are available which I have, as they are mostly for the smallest sizes (3/8"/10mm or less) that don't need much turning so I decided to compromise on quality a bit - handy with the odd difficult to reach bigger size but generally I would use the 3/8" set.
I suppose there is an optimum chart somewhere for the sizes as there will be some overlap?
I would say: (metric as its easier to type, but take these to the nearest imperial sizes)
1/4" 4-14mm (is there a smaller size than a 4mm socket?)
1" for ships, tanks, steam trains, the Eiffel tower etc (yes I know the Eiffel tower is probably riveted but I was going for comedy effect.......)
I also have a small rail of 3/8" drive deep sockets handy for some things (3/8-3/4" AF) and I also have two deep sockets in 1/2" drive - 1/2" and 9/16" AF
I have a small rail of 1/4" drive deep metric sockets 5.5-12mm - never used them!!!.....I didn't buy them specially, they came in a tool box I bought for the toolbox mainly but there were some useful tools there too
As MrBounce says - you can get carried away.......