I am surprised no mention of the gold standard: Tomoe River 52gsm. I’ve tried nearly everything in the market during the pandemic and they are simply the best particularly for fountain pens.
Too bad it's OOP now. I'll miss it when my stock is gone.
The original one yes (TR7), but a different company (Sansez) has started producing it (informally called TRS). First tests look surprisingly good, so there's hoping...