Usually a punch. I dig my Xikar 11mm on most parejos, but I'll straight cut lanceros, maybe coronas. I'll also use a smaller punch sometimes if the cigar feels light and like the draw will be too open. I started doing that months ago and dig it. It also helps to restrict the draw some on larger ring gauges. If I'm wrong, I just punch around the edges of the first hole and open it up more.
Going to check out v cuts more. I haven't often used them, not sure what it will add. I have some cheap v cutters, might should invest in something better.
As far as teeth, I have opened MANY a parejos with my teeth. You don't "bite" necessarily, and you certainly shouldn't chew. You just kind of scrape the top of the cap off with your teeth. Once you get the hang of it, it's easy, efficient, and you always have a cutter with you. They've already cut the cigar for you at the factory. You just need to remove the end piece.