I pretty much exclusively ordered from My little Customs until very recently. They've always been fantastic for me, They answer questions really quickly, really fast shipping and they're super friendly. Elise even sent me sweeties with one of my orders:) Not that that's really relevant I suppose.
I usually do whatever I can to avoid ordering from dollyhair, just because of my experience with not getting questions answered and my order took 5 weeks to arrive:( I have placed an order there recently to get my hands on some of the new colours and Blueberry Muffin. If MLC stocked them, I would buy them there instead.
I placed an order from a competitor about a week ago and got my order within three days. Big thumbs up there:) I can't say a lot about the customer service there since I never had to ask any questions, it went so smoothly, I had nothing to ask about:)
I have noticed that the hanks from dollyhair were smaller that the only other time I ordered from them though, that was about a year ago.
Some colours always come in smaller hanks though, no matter where you order from:(
Edit to remove some content - thanks Jupi