Everyone who spends time in Namba learns to love Zundoya. Their specialty is a powerful tonkotsu, tuned to your liking. It's open 24 hours, so this is a prime stop for pre or post-drinking noodles.Tonkotsu
Iizumi's shio is a model shio: simple and salty, with a welcome arrangement of additional flavors brought in by the toppings mixed in. It's a clear soup that takes a lot of notes from the sesame seeds and green onions sprinkled about.
I know I mentioned this before in the Umeda section, but I will mention Mitsukabozu here again because it's that good. So many different varieties of miso ramen, all of them great. Go already!