Ohira Asagi (JNS 4, Watanabe HS-55(ish), Aframes 8.7): I have used these examples and while all had their own personality they were very much interchangeable. 4-6k edge if compared to synthetics. All on the softer side of hard and fast.
Yaginoshima Asagi (JNS 3.5, Watanabe HS-50, Aframes 8.4, and one other without a listing): Again, all had their own personalities but all very, very similar in use. Fast, fine and on the softer side of hard. About a 6-8k edge when compared to synthetics.
Oouchi: (JKI: No scale listed but said to be not too hard and not too soft. If I had to place it I'd say it falls between a JNS 3.5-4, Aframes 8.2) Again, these two stones were similar, very similar, in use. Fast, fine and on the softer side of hard. Probably softer than the other two if I had to say. Around 6-8k as well but I'd say closer to 6 than 8.
Any of those stones would be fine with me as a general purpose finisher on a narrow bevel. I'd blindly keep any one of them but I'll tell you which I did in fact keep. The Yagi listed as other and the Oouchi from JKI fwiw.
Which stone I use the most is none of the above though. That is in fact a Hideriyama from Jon B at JKI that I have fallen in love with over the past few years. However, I have used a few Hideriyama that were turds to say the least. Take that for whatever it is worth.
What I will end with is this. Buy from a trusted vendor/member who tests their stones. Tell them what you want and be specific. The name/mine associated with the stone at that point shouldn't really matter. Used stones on this forum are a good way to go too.
And you thought I was going to say Aizu.