Let's not get all reactionary about this... hold on...
[2-hour rant about those (deleted)s at Scam.co.uk]
right, got that out of my system...
Anyway. I've been building up PCs since the 486 days, so what I'm posting here is a pretty good cross-section of my experiences from then to now.
FWIW, I've owned 4 Asus boards and 3 Gigabytes, in addition to 3 Asrocks, a number of ECS (including my 2 current mobos), 2 Epox and some other randoms. I always choose a motherboard based on features and stability and the price I pay for those.
Okay - of the 4 Asus boards, 1 was an abortion from one end to the other, 1 worked beyond what I wanted, 1 was okay and the last one I had just wasn't worth what I paid for it - nothing wrong, just not up to my standards. Socket 7, S370, S370 and S478, in that order.
Of the 3 Gigabytes, 1 again was an abortion, 1 was pretty good and 1 was okay(ish). Socket 3 (486), Super Socket 7, S370.
My point is, both brands have good and bad boards. Now, talking as someone who works in a PC shop, we prefer the Gigabyte boards due to things like 3 year warranty etc etc. which the Asus also has. We sell less Asus boards due to their higher price, go figure. I personally would love to sell more Asus and less GB boards (more commision, haha!), go figure.
What I like most about the DSx GB boards are the all-solid capacitors and the nifty features. So yeah, your scam.co.uk rep is clearly after more commission.