I'm pretty new to knives so I don't know much about many designers other than their production recreations. But I'll do my best.
Ken Onion. I really like a lot of the lines and shapes he uses. Three of my favorites are the Leek, Spec Bump, and Random Task. Each for different reasons. The Leek is svelt and elegant. It has an understated beauty and rides well in the pocket, which is a practical effect of the design. The Spec Bump is curvy and sexy, but also very ergonomic. The Random Task is simple and purposeful. And his customs (which I have only seen in pics) are some of the best looking knives I have seen. His same great design style that I know from production Kershaws, but with incredible-looking materials.
Neil Blackwood. I think his customs are a little "too much" for me. Too wild. Too much like a concept car versus a real car. But I think the Skirmish and RUKUS are two of the best looking production knives. So while his typical customs may be too much for me, I think his designs are great and he is really talented.
Sal Glesser. I'm not just kissing butt since you are here. I am into minimalist cars and motorcycles- you know, form following function and no excess like radios and A/C. Many Spydercos follow this philosphy. I think the Delica and Endura are two of the great modern classic knives and were very innovative.
I wish I knew who designed the Mcusta Kasumi. That is, in my opinion, the best looking knife that I have ever seen.
I also think the Sebenza looks great. I think it has an understated beauty and elegance. I also really like some of the graphic versions (both the production ones and the unique ones I have seen). So honorable mention to Chris Reeve and Lisa (who does the unique graphics now while Chris did the old ones).
I think this is a great combination of beauty and simplicity.
Can't wait for mine to come!