I have not heard of a lot of Nikkos going wrong. I have one that I bought when they first came out and the clicks are still going strong on that one.
The quality of the image can vary so I would suggest trying before you buy if possible but that is not always an option.
I have had quite a few Nikkos and not had any with turret problems - I currently own a Mk1, Mk2 and Mk3 so I am not telling you anything that I wouldn't do myself
It would be worth trying a Falcon - I have never looked through one and they may be very good??? I just know that the Nikko will take you wherever you want to go in FT (from club shoots to the world champs if that is what you want).