It's been said already but for a DJ to really hold attention they've got to do both - concentrating too much on long smooth mixes runs the risk of losing some of the crowd and having people drift off but too much chopping (especially when it's done badly - nothing more guaranteed to spoil a stomp than a DJ chopping the music every 8 bars and missing the first beat when they drop it back in again) can just get irritating and spoil the flow.

The music being mixed matters a huge amount too - it's all about finding the style and approach that best complements the records you want to play and not overdoing any one aspect of it.