Depends on the commute.
I used to have a quite long commute on the subway - 1.5 hours in one direction. What worked well in the morning was getting up a bit earlier, doing some exercise, eating a good breakfast with time to spare, then relaxing with a book on the train (fiction, non-fiction, really anything that tickles my fancy, something engaging) - especially nice buzz after a morning warmup. The evening reverse commute wasn't that much fun, the best use of time was leaving a little earlier, tidying up non-urgent 'for info' emails for 40 minutes, then some music as a barrier between work and non-work; not every waking moment needs to be 'productive'.
With another company, with a shuttle bus, an hour each way, most of the bus slept but I continued to read, stared out of the window at passing fields, plus found reading at the end of the day OK when comparing to the subway at the end of the day. I also had a 'bus buddy' which consisted long fun conversations if we were on the same bus. I also didn't eat anything for a couple of hours before leaving - things settled on stomach tended to make me sleepy in afternoons.
I understand the tube will be getting mobile reception in the coming months. It will be interesting to see if London transitions to carriages of people with their heads in their phones like most underground systems around the world. I hope not; implicit pressure to check and respond to emails before and after work can be pervasive/invasive - busy doesn't mean productive.
I now walk about 20 minutes, just walk, with no distractions from walking, arrive a bit earlier and keep up reading or other activities through an extended lunch break.