Adding my voice to checkboxes. The first time I encountered this I had to read each box several times to make sure I was picking the one I wanted. This is especially true when each button contains three different items. Checkboxes while more clicking is faster for me.
On an added note, but slightly different. I've played a lot of dominion, yet I still couldn't tell you all the different card types any particular card has. Consequently, I keep having to right click to look at each card to determine which card is the best to reveal with the Courtier. If you want to minimize clicking in that case the card types should be visible straight from the main play area. If there isn't room perhaps icons for each type? Although iconography can quickly become problematic too. For every solution there's another 5 problems