In my garden at the moment, the Alkanets are burgeoning. They're the biggest thug in my garden, although there are also problems from squirrel-planted hazel trees, Aquilegia and Raspberries, although it's all a question of perspective. The bees love the flowers, and raspberries are tasty.
I found this glorious sight of two happy garden thugs locked in mortal combat out on a walk. The periwinkle can smother a garden bed (though mine has remained persistently tiny, weedy and almost dead, probably because I bought a pretty dark purple variety) and nettles form dense rootbeds that crowd out everything else.
Who will win?