A browser based on an open-source codebase with many people auditing its source-code and network traffic (there was much paranoia about Chrome when it was released). And even in that case, you have the choice to use a completely open-source browser that has a different stance on user privacy (Firefox).
An NPAPI plugin that can be easily disabled.
A third-party BOX MITM all your secure connections without your knowledge.
I don't think the above are comparable in magnitude.
You're right--the third is the worst by far. And this proves that you can't trust a pre-installed, commercial browser until it has been thoroughly audited by independent researchers.
A browser based on an open-source codebase with many people auditing its source-code and network traffic (there was much paranoia about Chrome when it was released). And even in that case, you have the choice to use a completely open-source browser that has a different stance on user privacy (Firefox).
An NPAPI plugin that can be easily disabled.
A third-party BOX MITM all your secure connections without your knowledge.
I don't think the above are comparable in magnitude.