Honestly, that's tough. My fuel impact driver by far sees the most use. I love that thing. As an electrician the bandsaw is a God send. Makes great cuts and doesn't bounce the material around. There is nothing better for cutting track lighting and wire mold. Does a great job with bolts and obviously pipe. I use the bandsaw for a lot of things. I like the hackzall a lot too. The sds hammer drill is great as well. I'm impressed with the circular saw. It's perfect for my needs. The only m12 tool that I own that I was disappointed by is the vac. Doesn't do a very good job with sheetrock or concrete dust, unlike the m18. Makes it useless to me. Oh, I forgot about the multi-tool. It was too underpowered to be useful for me.