Currently I am using opencart 1.5.5.1 and MariaDB on my website. I want to upgrade my configuration. I am thinking for these listed below.
PHP 7.3 (Latest)
Opencart 3.0.3.1 (Latest)
Nginx
MariaDB
Can anyone help to suggest, is this the best configuration or not? Is this configuration help to improve my website performance?
You should wait for some bugs to be cleared from OC 3.0.3.1 before going there.
PHP 7.2 (tested and working just fine) Opencart 2.3.0.2 (stable) or 3.0.2.0 Nginx MariaDB
I would also recommend using CDN such as Cloudflare. Also using the right theme and modules is sometimes more important than your OC version.
Dont forget to look at this link especially this for OC 3, and also OC Forum.
You can also research LiteSpeed server instead of Nginx - is has a proper OC module now and gives very promising results.