On the backlink side, I would care more about real traffic than DA/DR.
I would focus on relevant guest posts, niche edits, and genuine brand mentions. they take more effort than buying link packages, but they are usually better.
for finding sellers that are not just selling spam, don’t only look at the marketplace thread. check their history, how long they have been active, and whether they have real discussions rather than just bumping their own threads.
On linkwhisper, I have actually used it myself and honestly got fed up with it. most of the suggestions felt like they were based on matching words or phrases, rather than understanding whether the two pages were actually related.
so I stopped using it. I use screaming Frog and a simple spreadsheet now. It takes a bit more work, but I would rather choose the links myself than waste AI credits. if you have a small site, you can use the free version of Screamingfrog too.
It takes a little more time, but for a smaller site I would rather spend that time than keep paying for AI credits.