Oil-based stains penetrate deep into the wood grain to provide long-lasting protection and rich color. However, they have a strong odor, take longer to dry, and are more difficult to clean up than other types of stains.
Water-based stains are quick-drying, have low odor, and are easy to clean up, but they tend to have a more uniform color and don't penetrate the wood grain as deeply as oil-based stains.
Gel stains are thicker than other types of stains and are ideal for use on porous or irregular surfaces, as they won't run or drip. They also tend to produce a deeper, richer color.
Regardless of the type of stain you choose, it's important to prepare the surface properly by sanding and cleaning it, and to apply the stain evenly, allowing enough time for it to dry before applying a clear finish, such as polyurethane.