The only tower I fully recommend to pay the entrance fee to make it to the absolute top. The view is stunning and fully overlooking Tokyo. From there you can spot most major landmarks too. However, the experience not fully appropriate for those afraid of heights because the way down is through semi-see through stairs.

You can buy tickets online in advance or by the entrance. Personally, we got our tickets on the day of visiting when we arrived and din't buy the guided tour.