I guess it depends on how you are going to use your knife. A serrated blade provides a more versatile edge and in my opinion has more aesthetic appeal than a straight blade. However, it will generally cut you a lot worse than a straight edge. The first time a got a good quality butterfly knife was about seven years ago when I purchased a BM 45 comboedge. I messed up on a manipulation (trying to do it too quickly) and rolled my thumb over the blade while it was still in the handle. Well, the blade rotated out of the handle and took a decent part of the side of my thumb with it. The fact that it was the serrated part that bit me made matters even worse as the cut was jagged and it was very difficult to stop the bleeding. So, if you only plan on manipulating your knife and not using it for any big cutting chores, I would go straight edge. After all, even the best of us get cut now and again, and my theory is that if youre not getting cut occasionally, youre not challenging yourself enough to improve to the next level. At least with a straight edge your blade-related injuries will be a lot less severe and you can get back to flipping more quickly.