Have not used Luminar 4, however outside of photoshop or lightroom, paintshop pro (PSP) is probably the next most mature photo editing application available. It has been around for as long as photoshop, has similar editing menus and algorithms. I used PSP for quite a few years.
https://www.paintshoppro.com/en/prod...?hptrack=mmpsp
Lots of video tutorials on youtube for PSP as well. Youtube is your friend when learning how to edit photos well.
And many popular plugins like Nik Software and Topaz, are available for PSP.