Bugs. I've flashed a load of phones (Sensation, GS3, One S, One X+, Nexus 7) and not one of them has been without the odd bug. Sometimes there are very few bugs admittedly, but the best bit about my Nexus 5 was that I didn't want to flash anything onto it, because the OS was perfect. I want the same from my next phone, but I don't want a 6 inch screen/£500+ price tag.Tbh, get the phone you want, then flash a stock rom over.
I know there's a fear over flashing, but it really is straight forward. Once you've done that, you have the phone you want with the OS you want, what more could you want? :smiley:
So tempted with the OnePlus One!