Shrooms is better than Bulwark for both training size and the type of troops it gives you (at least for elves - Archers are far more useful than Sword Dancers). This is even with a small/modest number of armories and the gap just gets bigger the more Armories that you have. You will need a lot of Armories to have a long training queue in the late game, assuming that you also aim to focus on leveling-up your training speed improvement Ancient Wonders (Needles, Flying Academy and Victory Springs).
I have 15 Armories @ level 41 (these give 830 training capacity each). These add up to 12,450 training capacity.
I have a level 13 Bulwark and it gives me 5,756 additional training capacity (I have the current maximum possible squad size - 7,674).
I also have a level 16 Shrooms and it gives me 14,760 additional training capacity.
Total training capacity = 32,972. Each full training slot adds 4 hours, 30 minutes and 26 seconds to my queue. Full queue = 22 hours, 32 minutes and 14 seconds.
Of course, Bulwark has the advantage of being available two chapters earlier, I still skipped it originally, waiting for access to the Shrooms. I only built the Bulwark much later when I had more free space in the more recent guest race chapters. Bulwark was a really, really bad investment before the tournament format was changed a year or two ago, as you wanted to skip the optional training size research upgrades before, as these hurt your tournament play, but this is no longer the case, so the Bulwark isn't anywhere near as terrible as it used to be, but it still comes up short compared to the Shrooms.
