I have a bunch of different LNBs and LNBFs
With the exception of some older noisy models that might be slightly defective and have badly off-key DROs, I would say that there are only minor differences in reception quality.
Among those good LNBFs, I have a GeoSatPro UL1PLL, a GeoSatPro SL4-PLL, a Maverick MK-1 PLL (not sure I got that model name right), a couple Inverto Black Ultra, and a few Inverto Black Premium
The Inverto LNBF are giving me a very slightly better signal quality than the UL1-PLL. Maybe 2 % increase in quality on the Amiko miniHDre.
This said, I believe they are DRO LNBFs, so there might be some trade-off on very narrow signals, where the PLL would be more stable.
The main problem with the Inverto LNBFs is that they don't appear to have a distributor in North America. I see some on ebay but at grossly inflated prices or prohibitive shipping costs. (I took advantage of a family visit to Europe to get a few of them)
Of course the best LNB is a larger dish...