Not suggesting to get the ysp-2700 (16 drivers) or ysp-5600 (32 drivers) (and sorry for my typo). They are rather expensive although I don’t doubt they might sound good and loud with a fair amount of power behind them. Yamaha yas-109 has a “clear voice” mode, bose doesn’t have any according to rtings, denon has 3 dialogue enhancement modes.
I have never looked at soundbars (yet) but noticed some community user complaining the bose solo 5 is no louder than the tv (not that loudness = clarity). Like all things, definitely suggest have a listen before dropping cash on it.
Apparently, Yamaha yas-108 is the same as yas-109 without Alexa support. Review below from rtings for both so hopefully there is some consistency. 
Bose Solo 5 reviews:
- Bose Solo 5 Review - RTINGS.com
- Bose Solo 5 review: An ultra-compact soundbar | Expert Reviews
- Bose Solo 5 review | What Hi-Fi?
Yamaha YAS-108 review:
Denon DHT-S216: