Both are good in their own ways
If you want relaxed beach kind of vacation head to Bali
HOngkong will give you more cosmo & vibrant kind of experience. Also Hong Kong is more expensive than Bali
Bali has more to offer now for the solo travelers. party hostel's boat rides are available now. hire a bike and you can explore more remote areas. staying in hostel and making new friends are easy in Bali.
Hong Kong is modern skyscrapers city while Bali is natural beauty with beaches, natural attractions so decide what you like and just head on there. thanks.
Both are good options. Bali is perfect for natural beauty as well as it's cheaper than Hong Kong. if you want to enjoy the skycrapper and night life, then Hong Kong is better.
Both countries have very different vibes all together and also the time taken is different. So if you have 7 to 10days in hand and wanna experience natural beauty, best of sunrise , cleanest beach and experience luxury ( like private pool villas) and temples So Bali is the right place . But if you have some 5 to 6 days in hand and you wanna visit Disneyland , Macau and experience metro city with night life So it's the place.
We would recommend you Bali if you have time in hand
Hongkong is expensive and you will face language problem there so it's better to go to Bali as you can explore and do some adventures like skuba diving plus you'll get to meet some girls.