You're probably not a target and Google is not the NSA. I don't think capitulating and voluntarily giving them your data helps.

I get utility in return, ie Google's ability to provide better results based on previous context.

I wouldn't call them better results. I for one don't find "the filter bubble" desirable.

https://en.wikipedia.org/wiki/Filter_bubble

Concerns about this seem overblown to me. I get regular comparisons as I have a tablet device that's not linked to any account and also use more than one search engine or browser. I find a marked improvement in the quality of results when I'm logged in, particularly when I'm researching legal or academic topics where I'm more interested in primary sources and long-form article coverage than in (more popular) blog and mainstream news outlet coverage. The other benefit is the personal blocklist, which automatically filters away a vast range of stuff which I know to be crap.

If you don't want to give them your data, you mustn't use Google. Logging out is nothing more than a placebo.

>If you don't want to give them your data, you mustn't use Google.

That is not sufficient. Recipients of your emails must also not use any Google services (also recipients of their emails etc).

Not using Google is probably the best solution. If you still have to use it for whatever reason, don't give them all your data. The only thing you really have to give them is your search term.

Lack of data is also data. How many people do you think send absolutely empty requests? It probably makes you extremely unique.

Of course there is no proof, but could we agree that Google would make an exceedingly useful front-office for the NSA?