You can do a better job with good high end Paint Brush
While it is possible to do a good job painting with cheap brushes and roller covers, you can do a better job with good high-end ones. But they aren't cheap.
How can you tell a good brush?
In the store, test it’s flexibility by giving it a few strokes on a firm surface like you were applying paint to it. The hairs of the brush should flex but not spread too wide and then spring back to shape quickly. Next, fan the brush bristles between your thumb and forefinger to check it is firmly bound to the stock and evenly set.
The type of bristle will also affect the brush’s quality. China hog bristle is the best natural filament to use with oil paints. China hog bristle can be used only with oil-based paints, because it absorbs water and becomes loose and floppy. It does not have the long wearability of polyester and nylon brushes.Oher natural hog-bristle brushes are recommended for use with varnish and lacquer in addition to oil-based paint.
Nylon and polyester (the best synthetics) are tipped, flagged, and tapered individually during manufacturing. Quality brushes are made with multiple sizes of tapered filaments similar to pure bristle brushes. The flag is maintained during long use. Generally, the longer and thicker the brush made of tapered nylon or tapered polyester, the quicker the job will be done.
The "heel" is the part that fits to the handle. A good paintbrush will have a well built heel and you can generally feel the difference between cheap brushes and premium ones. All good brushes also have an empty space where the bristles are placed in the heel.
This space is made by a wedge and you can see the space if you check between the bristles. The spacing is where the paint reserve is going to go. Do your best to avoid brushes that have a solid heel (in these the bristles are usually glued into the heel with no spacer) Look for the same design features for a brush used for latex paint but the bristles should be polyester (better) or nylon.
Handmade brushes, in general, are better and clearly say they are handmade to justify the premium cost. For both oil and latex though you want wooden handles and you want to see that the heel and handle are joined with nails.
When you're done using them they should be washed properly, combed , and wrapped for storage.