The weight for a texas rig comes down to personal preference and what best suits you. For instance: 1/8 ounce is suitable for a slow-falling lure in the water. 1/4, 3/8, 5/16 ounces are more suitable for sparse fishing and brush piles in a depth up to 20 feet down.  If you're going for deeper than 20 feet, consider using 1/5 ounce weight. It's great for bass holding.