I'm looking at jigs and there is three weights 1/4 oz, 3/8 oz and 1/2 oz which weight should I get?

The most common one that I use is 3/8. But I like to have a couple of each just in case the bass wants a slower or faster fall.

If I am dragging a jig along the bottom I always want a heavier jig that will hug the bottom and kick up some mud.

If I'm pitching jigs around specific targets, I'll go with a lighter jig because of the slower fall. If I am trying to penetrate cover or am fishing deep water I'll use a heavier jig.

It all depends on what YOU plan on doing with them.

I'm looking at jigs and there is three weights 1/4 oz, 3/8 oz and 1/2 oz which weight should I get?

You should get a couple of dozen of all three in 3 or 4 colors.  You can't have too many jigs.  You also should consider some 3/4 oz in the same colors as the other sizes.

Bank shallow out to 15' 3/8 oz & 15' deep plus or heavy vegetation 1/2 oz  

3/8 oz is the most versatile in my opinion

check out karus poll, a lot of ppl give opinions in that thread

I'm looking at jigs and there is three weights 1/4 oz, 3/8 oz and 1/2 oz which weight should I get?

ALL!