Avoid the Headland etc, unless you are grandparents who are primarily focused on visiting kids/grand-kids in TC or DB.
USRC is a good choice. But it seems to be booked up most of the time.
I have used agoda.com for years around Asia. If you can commit to booking set dates for check in - check out, then this is a booking forum which delivers good choice and value. Be wary of "kid unfriendly" hotels btw (more than one kid means two rooms).
Location near the MTR would be an advantage. If it is significantly cheaper to stay in Kowloon, then ensure that the location is close to the MTR etc.
Have a great visit