S series 7 or Next 4/8

My grandfather is wanting to get a new hearing aid because his is no longer providing the sound he needs. As we look into different aids we are unsure of which manufacturer and model to choose and we don't feel comfortable trusting the hearing specialists because they all recommend their brand. We are looking more specifically at the starkey s series (7) and the unitron next (4/8). They are approximately the same price so we are asking which make is considered superior.

Thanks!