If your looking at the high end decks then both are as good as each other really. It's just personal preference.
Same goes for the budget ones really.
I would say Numark though as I have found them to be reliable.
i would definately say that numark do better mixers, the quality is high even for the low end market stuff, and u get alot for your money's worth esppecially if ur spending a fair bit of dosh.
in terms of turntables. u pay for what you get. buy the low end stuff and its not gonna be amazing or particularly reliable. i know alot of people that got the numark battle pak when they first started mixing and ive heard alot that they fuck up after a while etc. almost everyone i know that had em upgraded within about a year of buying em. at the same time my mate has had numark ttx's for ages and they are fucking awesome, amazing torque and LED display on the digital pitch control is sweet. got another mate hu has numark x2 hybrid turntables which offer the same specs as the ttx but gives you cd play with vinyl manipulation (just like serato but u dnt have to put the needle on the special vinyl)
ive only mixed on low end stanton stuff which is standard poor quality really. i use technics 1210's all the way and live buy em. but im thinking of getting an x2 or summat similar as a third deck.
I got numark TT1625's about 2 an a half years ago, they were second hand at the time, an they still work well now, the torque has recently gone a bit dodgy on one of them but thats it... An considering I paid £160 pound for the pair I'm not gonna argue...