I think Darren always produces interesting choreography. There's always a story and a great movement to his dances. He uses musical accents really well.
Also, when Brendan gets a great routine together, it will be GREAT. Sometimes it goes horribly wrong with him, but I think most of his dances with Kelly were well-choreographed. The rumba, the tango, the AS and the VW were all interesting routines, even if the celeb dancing it wasn't particularly! I remember being particularly impressed with the spin he did on the VW.
And Ian. How could I forget?! He quite often does amazing choreography. Zoe's Tango, the quickstep with Denise, the AS with Jodie etc.
A lot of people on here really love Matthew's choreography, but I must admit I'm not crazy about it. I remember finding it all a bit "d, u, double l" in Series 4 and criticising him for it. I think it was Alesha's superb talent that made it interesting last year. That, or perhaps, his best choreography only comes out when he's working with someone like Alesha.