The Google Home Hub and Echo Show are both formidable smart displays, but they are very different in terms of price, size and features.
It depends on both your preference and usage. Most people have a favourite, they would either be more inclined using Google Assistant or prefer Alexa. Maybe you could share a little more on the main things you'd be using these displays for and a best fit can be decided? Personally, I would go for a product that has Google Assistant because I feel that it is more intuitive than Alexa (which is why I'm planning to get myself a Lenovo Smart Display).
Only Google Home Hub can get YouTube but music videos are excluded unless you have a subscription to YouTube Premium. My recommendation is to save your money and get neither until they are mature products.