As bullseye has said there is always going to be strong opposition on either side. As for the build quality that's my personal opinion, I feel eclipse put more effort into their product, I'm not saying dye don't, it's obvious they do otherwise they wouldn't sell any markers. I have had a few bad experiences with dye as have people I know, but then I also know people who have never had issue perhaps I've been unlucky but the bad experiences have put me off for the time being.There is still a dye uk, I think they moved the stock to Germany?
At the end of the day your gonna get eclipse fanboys saying ego and dye fans saying dm..... As for build quality they are pretty much identical, I deny the claim that eclipse is 'of a higher build quality' absolute rubbish.....and I've used tech support from dye a few times with no issues.
Again they are both great markers and prices are crazy atm so just get the one you want if you have the cash