You hit the nail on the head when you mentioned speed. Speed is key. Drop shadows, gradients, fancy fonts, complex colors etc. contradict the point of using a wireframing tool in the first place.
A few weeks ago I gave it another try and it just clicked. What I have found is that the product has matured and the community is strong and provides the missing pieces. It's become a regular part of my toolkit.
For me a wireframe tool is useful for building a minimum viable product. If you're looking for something that is pixel perfect you will continually be disappointed with what is out there.
I tend to ignore most coloring and shadows unless I need to make a clear distinction in a part of the UI. Sometimes without color variations your point is complete missed by the viewers.
I like balsamiq for the friendly keybindings and just easy manipulation of the widgets. It's been fairly bug free for me for the last two years that I've used it.