I used to use an Olfa 60 mm, especially if I'm standing and cutting many layers - the one with the squeeze handle which makes the blade come out and retracts as soon as you let go. But when I saw someone at my favorite quilt shop cutting with a Martelli, I knew I had to get one. Now I use that most of the time, especially when paper piecing, since I'm sitting then, it's easier on my arm. If you want to cut many layers, you just need to use a larger diameter blade, no matter what brand. I always wait to buy any rotary cutting tools when the store has them on sale or I use a coupon, then the cost isn't such a shock.