Have a nice evening (my workday is soon ending.)
Whenever I buy a product, I always look at the gold standard and see why it's the gold standard.
Then I try to emulate the best points with my budget in consideration.
I would consider tubus to be that gold standard and would start my search there for racks.
https://www.tubus.com/produkte/
For attachments, I would start with Rixen & Kaul.
https://klickfix.com/en/#slide-3
https://klickfix.com/en/products/
and select "Carrier" as the attachment point.
Prices are reasonable but you might want something less expensive. Quality is unsurpassed.