Yep, it's all about direction. The Oedo commute from Hikarigaoka in the morning is brutal; I live on the line and avoid it in the morning as much as possible. There may not be as many people as there are on the Ginza Line, but the train is much smaller so it feels just as jam-packed (too crowded to get your phone out of your pocket most of the time). OTOH, it is basically never crowded on the north side between Shinjuku and Iidabashi/Ueno.

For a while I was taking the Tozai Line eastbound in the morning, from Nakano toward Nihonbashi. The through trains from the Chuo Line are usually packed, but the trains originating at Nakano are never particularly crowded and you can often get a seat at Ochiai or even Takadanobaba (where a bunch of Waseda people usually get on, and then get right back off at the next stop). These trains basically alternate, so if you get a crowded train at Nakano, Ochiai, or Takadanobaba, it's simply a matter of waiting a couple of minutes for the next one. Lots of variances in the system like this, IME.