I’ve made a few observations after ten weeks of daily commuting to London.
The unpleasantries of the rush hour can be alleviated somewhat by choosing your train carefully and getting on at the right place. I always catch the 07:25 train to London Victoria at Horsham and go for the rearmost carriage, and so far I have had a 100% success rate at getting a window seat. Most of the stations between Bognor Regis and Crawley have short platforms, and consequently the front of the train is generally much more packed out than the rear. I do not recommend getting on at Littlehaven: its platform is only four coaches long, but more people get on the train there than at Horsham, and it can be a bit of a crush at times. Then you have to jostle past people through several coaches in order to get a seat.
This effect is even more pronounced on the way home in the evenings. On Thursday I made the mistake of going for one of the front four coaches, and even though I had a seat, it was not a pleasant experience. The entire Littlehaven crowd pile in to the front four coaches right from the word go, rather than spreading themselves more evenly through the train and moving forward once we get to Crawley. This means that the back of the train is definitely the place to be if you are disembarking elsewhere.
I avoid the Underground like the plague. London buses may be a bit of a lottery in terms of overcrowding — I’ve had both good and bad experiences on the 507 — but at rush hour, the Underground is guaranteed to be so packed out that it makes a Kenyan matatu look like an intergalactic void. However, as I am working just under a mile from Victoria, it is cheaper, less crowded and more healthy to walk, as well as giving you a good bit more elbow room at only minimal cost in terms of time.
Finally, the best place to sit in a train is near the middle of a carriage. You get a pretty smooth ride there, whereas by contrast you get jolted about quite a lot near the ends of the carriage. It’s much the same reason as why the middle of a boat is where you’re least likely to be seasick: the carriage acts a bit like a lever, so the ends tend to wiggle about a lot more. Another thing about the ends of the carriage is that they can be a lot noisier if the doors at the end get jammed open.