Either cable with the HDMI adaptor would be better than the ps2-to-hdmi,What about PS2 to HDMI Adapter vs. Portta + OEM Component?
Both the portta and ps2-to-hdmi have the downside of no 240p support (~3 ps2 games and most ps1 won't show up)
But you can think of the ps2-to-hdmi adaptor as a super cheap component cabled, and a super cheap hdmi converter all smashed together, that would be a bad idea normally, (you don't want to cheap out on anything that Handles analogue)
But these cheap combo units go for under $10, so they really cut corners, The image quality and contrast would not be as good, and you'll likley get a fair amount of interference.
The portta's not perfect, but it's a solid budget Analogue to digital converter, and it would be working with a much cleaner signal.