I've been using MT Power Drumkit until I can afford better. Stll not there yet due to higher than expected expenditures last quarter. HOWEVER !!
I had EZDrummer 2 at the top of my list for when the day comes, now that's been bumped to EZDrummer 3. I'm intrigued by it's newly added Bandmate feature which analyzes audio tracks (guitar, etc.) and writes a drum track that actually works and sounds decent (per the promo video, anyway). That alone would increase my creativity.