I have difficulty choosing a toothbrush. I have already tried many. How can I know which one is right?

Toothbrushes can broadly be divided into three groups: manual (conventional and interdental) and electric. Conventional manual toothbrushes come in different sizes and shapes and in three different degrees of hardness: soft, medium and hard. Size and shape are a matter of personal choice. The hardness of the brush can be selected according to gum sensitivity. The more sensitive the gums are, meaning they recede due to repeated injury during brushing, the softer the brush should be. I should emphasize that gum recession from the tooth necks and the occurrence of wedge-shaped erosions are mainly caused by an incorrect brushing technique. Most often we choose medium hardness.
Interdental brushes are intended for cleaning the interdental spaces in the papilla region. Interdental spaces are the main regions of habitual dirt accumulation. Most plaque and bacteria in the mouth are retained precisely in these areas. The thickness of the brush is selected according to the size of the interdental space. If the interdental space is too tight and the brush cannot be inserted between the teeth, we use dental floss instead.
Electric toothbrushes have come into use more recently. If we know how to use manual toothbrushes correctly, electric ones do not provide an essential advantage. In difficult-to-reach areas of the mouth, where maneuvering with a manual brush is difficult, however, this is not the case. Certain electric toothbrushes also massage the gums well with the vibrations they produce. Gum massage increases blood flow through the gums, which is certainly positive; faster regeneration after procedures, reduction of inflammatory processes...
In principle, every toothbrush is excellent if it is actually used.