Staffa Tour runs the segment to Staffa on the West Coast Tours Three Island Tour (mull, Iona, Staffa). I enjoyed it very much and had no complaints with their service.
Whichever tour company you take to Staffa, they all land at the same small landing. They will discharge passengers and then move off shore for a period of time to free up the landing for others. You climb a series of stairs to access the upper parts of the island and then hike a bit more to get where the puffins are.
It was pure pleasure to sit quietly and watch the puffins. There is also an option to walk along the lower part of the cliff to Fingal’s Cave. You will also see the entrance to this cave from the water.
Staffa tours were professional and did exactly what they said they would. I would highly recommend the 3 isles tour purchased through West Coast Tours. They have a nice video on their website to give you a taste of what the tour is like.