You're probably better off using the new Ektar 100 in 120 size instead of the Porta line. Ektar is newer with next to zero grain and does well with exposure latitude/dynamic range.
I've never tried the Ektar film but the Portra is nice. I have used both kinds and the results are good out of my Bronica. Is the Ektar c41 processing?
With a holga image quality isn't as important as composition and creativity. The camera has a lot to be desired in the quality control department. It's more of a fun creative outlet.






