What is the best increase to use for raglan sleeves?
There really isn't one best increase. It's personal preference. My personal preference is usually to just do KFB. It leaves a little bar on the increase, but that can be decorative.
What does your pattern suggest? That's usually the first place to start.
At the top of the page are videos. Look at the increases there. Here's some more help, too.
I think these are the prettiest increases I've seen for raglan sleeves or any other application. They really do "grow" nicely from the center sts.
Oh I like those! I've seen and done the second set, but never that first one and it's my favorite!
I'm looking forward to trying that one too.