Which branch of Debian is more stable?

Question

linux

I want to install Debian on my dad's laptop. The laptop is weak. They will mainly use the browser. So far, I have installed 8.0 (ie the current oldstable) along with LXDE, in connection with this question. Is oldstable more stable than stable? Or don't bother with it and put 9.0? As a matter of fact, the novelty of the packages does not matter, so the only criterion is security and the amount of resources consumed (older DEs take up less space and RAM). Nothing special is supposed to be done on the laptop, I just heard that older distributions are more stable. Is this principle true, by the way, that the older the more stable, and for how long?
Please be as detailed as possible with the pros and cons.

Answer 1

It is logical that Stable. Quoted from https://wiki.debian.org/en/DebianReleases.

Stable is recommended for production-level applications that require stability and security (servers, firewalls, etc.), as well as for those who are new to Linux. Testing is recommended for slightly more advanced users who want newer software and can submit bug reports and fixes to help Debian.

Answer 2

In such a case, the most voracious application will be the browser, here the OS branch does not particularly affect.