For me definately DiorShow Iconic, BUT only a fresh tube. I just bought my second one of it (and there's not a lot of times that I bought the same mascara twice) after a good 2month, which isn't a long time, I admit. I just really love this mascara for long clump free curled defined and volumed lashes, plus minimal smudging and easy application (which comes in handy when I'm travelling to my BF and want to put on my mascara while waiting for the train orso and only got a little mirror.
Oh and the one drug store masacare I liked a lot was Cover girl professionel, but I believe they reformulated it 'cuz suddenly it was all different. That actually was another mascara I repurchased. The ony thing I didn't like about it was the tube. It also came in a very nice 'blue black' colour which I loved. It was a dry formula (unlike Iconic) but worked very well for me: very clumpfree too and I remember being able to get my lashes to my brow bone.
The last mascara I ever repuchased was YSL effet faux cils: very nice smell (not that that mathers) and good all round mascara that like Iconic doesn't stay good a long time. It's not as clump free as Iconic I must say and it smudges a little on me.l