What I do
WordPress plugins, themes and applications.
My main focus over the last 6 years is custom WordPress / Woocommerce solutions. This includes crafting themes and plugins from scratch, implementing custom solutions using the majority of the most popular plugins, creating rest API based apps, optimizing security and performance. Of course, following the official codex along the way.
Laravel, Codeigniter, you name it.
If you want a custom PHP application then using a popular MVC framework is a must. I have experience with many, but my best bet is always Laravel.