Odd to hear people claiming their RTC's for 'nicest cat'. I mean, they might be the biggest, but being the Oscar of the catfish world I just don't see why they'd be considered nice. Unless it's the only catfish you have. That would make sense.
My "nicest cat" based on rarity, size and form would have to be my orinocodoras eigenmanni. I'd claim my acanthicus adonis but they're pretty common.
The big one in the middle.
Next to a normal platydoras armatulus for size reference
I have a lot of catfish, but if the house were burning down, I'd toss this one fish into a bucket and run.