The logitech g700 has side buttons, however they are very easy to press if you hold it with a claw like grip, even has a place to rest your thumb under the buttons. It also has four buttons on top, default is set to dpi changing on the fly. Up to five different levels in fact, you get to set what the levels are. The side buttons are not exactly what you asked for, I myself took a while to find a position to hold the mouse and press the buttons with.
If you are a person who likes to rest their hands on the mouse all the time, this mouse may not be good. The way I found to hold the mouse was to pull my hand back and sort of hold the mouse with my fingertips with my thumb just under the buttons allowing for access to them quickly. However the buttons don't get in the way whenever I'm web-browsing and I wan't to hold the mouse normally.
It is wireless but it can work as wired with the charging cord, and unlike most wireless mice this mouse loses no response time in wireless mode.
Did not mean to go into review mode, wanted to give you my thoughts on this option. This mouse has very easy to reach buttons if the mouse is held in a claw like grip.
Edit: OH you meant stacked buttons, I thought you meant top buttons. Silly me. Yeah this mouse has four buttons on the side, two rows of 2 stacked on top of each other.