Ring slings are a versitile option and can be used from newborn to toddler. The downside is that the weight is carried on one shoulder and so as the baby gets bigger the length of time it is comfortable to carry for becomes shorter.
Shoulder styles vary and so it is worth trying both one with a gathered shoulder and a pleated to find which you find most comfortable. They can also be made from cotton as well as woven fabric with stretch.
Ring slings can be n economical choice with many of the budget brands costing under £40.