Currently on a Luksusowa kick and have been since going to Poland recently. Good, clean, and it's cheap. Hard to beat that combo.
Edit: Another decent (and super duper cheap) one that I've had here and a ton of in Poland is Sobieski. Not as good as Luksusowa but you can get a handle of it for less than a decent cigar and it mixes just fine.
Luksusowa has now replaced all the more expensive vodkas I used to keep in the freezer. I actually prefer the taste of it (which is truly all that matters) and would still buy it at a much higher price.
Edit2: My true favorite is probably Zubrowka (the Polish one made with bison grass, which is illegal to import to the US--the version they sell here is crap).
Edit3: Wow, looks like I've become a Polish vodka whore
