Straight.
Sort of.
Confession time:
I use an exacto.
For most, I just slice the "skin" of the wrapper off the end.
For torpedos, I take off a small amount off the tip.
For flat heads, I cut a small circle in the end.
The blades are dirt cheap, I simply replace as soon as it gets dull, and I can precisely trim just what I want.
Used to use guillotines, but my last one got dull about a year ago.
My cigars are in my office/workshop, so I grabbed an exacto one evening to use temporarily, and never looked back.
I look at the cool, fancy cutters from time to time, but I've had nothing but success since I started cutting this way, so I just keep spending that money on cigars instead.
<shrug>