That's fine if you want a PC which is totally orthogonal to what the Pi is originally for.

I have seen this comment a few times, why do people hate micro hdmi?

Micro HDMI is basically a non working connector. It baffles me how it was even approved. One of the requirements of a connector is to work. Micro HDMI doesn't work. Sure, it might look like it's working (if you take a picture of a connected device) but in practice it doesn't work. Just a slight touch and you're losing signal. Immediately one might think that their connector, cable or device are broken. And this is a very valid guess. But the connector is not broken by accident, it was broken by design. A consumer connector should not require an additional exoskeleton to work. It means it's broken by design if it does.

because it's not popular and less durable. I can forgive the use of micro hdmi on limited size product. But this computer 100% has enough space for full size hdmi.

I suspect they had chosen the same HDMI port as was on the SBC so as to reduce confusion for the consumer.

What's a reputable brand here?

Beelink seems to be one of the better brands. I own one and have no issues.