A few weeks ago I was going through the same decision making process. It was time to replace my Scubapro classic that I bought used after I got certified. The first BC I looked at was the Knighthawk. It's a great BC and people like it. There were a couple of drawbacks. There aren't real pockets. Normally I like to stash some stuff in my BC like an extra flashlight. It's hard on the KnightHawk. Also the BC seemed kinda bulky. It does not look like something that packs well.
I ended up ordering a Zeagle Stiletto from ScubaToys. It has great design, features, pockets, and packability. One of the cooler features is a quick disconnect for the BC inflator. The BC inflator screws onto the BC using a standard garden hose thread. So when you get home you can unscrew the inflator and attach a hose and flush the BC bladder. It's a whole lot simpler than the aerobatics I had to go through to clean my Scubapro classic.
I was particularly impressed with Zeagle's service. If you check out the Zeagle manufacturers forum and read some of the posts they really seem to care about the customer. It's nice to know that if you have a problem or question you can talk to someone. Also the owners really seem to like them. They reminded me of Mac users, they had the same loyalty. Both are great BCs and I'm sure either will work out. Cheers, Adam