I am planning a trip to Asia from San Francisco and I’m deciding between Eva air and Ana premium economy. I want to go on a premium economy that offers an exclusive cabin with dedicated lavatories separate from economy class as this offers the best value for premium economy. I don’t want to go on a premium economy that is treated like a forward extension of economy with shared lavatories. Does Eva air premium economy or Ana premium economy offers this kind of experience?

You do seem quite fixated on dedicated loos. Premium Economy Class With Own Lavatories

Of the two I've only flown ANA so I cant compare them. But I've seldom been on and airline where folks in regular coach/economy couldn't use the lavs in 'Economy plus' or whatever the premium economy class is called. Now --Coach passengers usually are barred from the Business and First Class cabins -- but on many planes there aren't four banks of lavatories so someone has to share

Took a look at a 77W seat map for each airline and ANA looks better for you. You might not have to share as much with the riffraff behind you but share with your superiors in front. But YMMV becuase your plane(s) might differ.

SeatGuru Seat Map ANA

SeatGuru Seat Map EVA Air

Seat guru is not accurate anymore and it’s outdated.

That's true but it kind of doesn't matter given that the OP was so wide open. That is each airline has multiple long-haul types each with multiple configurations. Without knowing the specific flights or even routes, the question can't be answered with any kind of accuracy.

Assuming the linked layouts are reasonable, I chose the ANA one as better. That choice was made because the forward part of the economy section had fewer rows betweenn PE and the first toilets in economy. The first row of economy is closer to the toilets in economy. But, the toilets at the front of PE are still closer to some of those economy rows. And the PE toilets are closer for many of the business class pax.

If I really wanted an answer to the question I would go to the airline website and start a booking to see the seat maps for specific flights.

I saw this site mentioned on ft as a better alternative to seatguru:
Hola - AeroLOPA | Detailed aircraft seat plans

What other options are there? The seatguru feature that I like is the ability to enter in the airline and the route or the specific flight number for a certain date. Aerolopa as links for four different 789 layouts, so which one is mine? Seatguru also has comments for each seat an user comments.