There are many different hearing aid styles, as people have various needs depending on age, physical activity, user dexterity, and the myriad of available features.
Please take a look at the following site for a visual guide of hearing aids: https://www.hearinglife.ca/hearing-aids/types-of-hearing-aids
It’s natural to gravitate towards the smallest possible hearing aid. However, compared to larger hearing aids, small hearing aids have reduced battery life, and lack certain features. They will also require extra maintenance as they are inserted deeper into your ear canal, and thus accumulate more ear wax. However, those who desire a fashionably discreet hearing aid will accept these trade-offs.