Hi Lili,
I don’t own a Mark Norris, but I have tried them out and can vouch that they are good harps. I have two friends who own them and can only find good things to say about them.
Teifi harps are also good. Yet again, I don’t own one, but know someone who does – he loves it.
The problem with choosing a harp is that once you have got past the stage of “Is it well made” etc, much of what makes it “Good” is very personal. Whilst videos and recordings are better than nothing, they say as much about the recording equipment, sound engineer and player as they do about the instrument.
The only way to choose between two good harps is to try them out in person. And that is not always possible.
So both makes are good – nothing wrong with either, and a lot very right with both.