I bought one of the acclaimed Pilot Iroshizuku inks last week. It's also the first ink I've bought at a store in-person. Here it is on my desk at work. I've been using it in a notebook that doesn't really show off any nice fountain pen qualities, but even so, I've been enjoying this ink. The purple color looks great, and it dries quickly, which is nice for a lefty.

Seems like every other fountain pen user besides me has used these before; do you have any favorite colors?