Lightning
I honestly don't like Nightcloud and Crowfeather- I never have, and Crowfeather is a trashbag who needs to get thrown away. Nightcloud deserves so much better, and I feel sorry for her for having such a pitiful cat for a mate. 
I honestly don't like Spottedleaf and Firestar either. Never have, never will. The two would have never worked out, and the constant forcing of their relationship by the authors just drives me up the wall.
I also don't care for Lionblaze and Icecloud, Lionblaze and Heathertail, and.. the odd ship of Cinderheart and Jayfeather. There are a whole slew of ships that I don't like- in fact, I barely like any canon ship, but that's besides the point. Also not a huge fan of Gray Wing and Slate, Clear Sky and Star Flower, and Turtle Tail and Tom. I still stand by the fact that Gray Wing and Slate was rushed as hell and their relationship would have been better had it been properly implemented into the series. Star Flower and Clear Sky disgusts me, because not only does she seem a bit young, she also goes from Thunder to his father, which is just plain wrong. Tom is just an abusive crapwad who I am so glad died.