The best choice would be Magpul. They are well made and well known.
budsgunshop.com/product_info.php/products_id/1131/magpul+pmag+30+round+ar-15+w+window+gen+m3+black

Magpul for sure! budsgunshop.com/product_info.php/products_id/1131/magpul+pmag+30+round+ar-15+w+window+gen+m3+black

You can use any milspec magazines. They all work equally well. The most recommended is the Magpul gen m3. If you can find milsuplus magazines they are usually inexpensive and mostly cosmetic issues.
budsgunshop.com/product_info.php/products_id/1131/magpul+pmag+30+round+ar-15+w+window+gen+m3+black

The best magazine to use in the Ruger Harrier 5.56 NATO is the Magpul PMAG Gen M3 30-round magazine, which is recommended for its reliability and durability. This magazine is compatible with the Harrier and widely used among AR-15 platforms.
budsgunshop.com/product_info.php/products_id/1131/magpul+pmag+30+round+ar-15+wwindow+gen+m3+black ,
Stay safe & have a great day!

The best and most reliable magazine for the Ruger Harrier 5.56 NATO is the Magpul PMAG Gen M3 30-round. Users and reviewers consistently agree that these polymer magazines provide flawless feeding and superior durability in standard AR-15 platforms.Top magazine options for your Ruger Harrier include:Magpul PMAG Gen M3: Widely considered the gold standard and best-in-class for reliability and ruggedness.Lancer Systems L5AW M 30 RD: The best translucent magazine on the market, combining the durability of a steel feed lip with a visible round count.CPD Duramag Stainless Steel: A top-tier metal option if you prefer the classic feel and durability of a steel magazine with anti-tilt followers.

Hi and welcome back. This will be subjective, but I have tested and rated equally well The Magpul M3 Windowed and the Lancer L5AWM magazines : budsgunshop.com/product_info.php/products_id/1131/magpul+pmag+30+round+ar-15+w+window+gen+m3+black ------------------------------------------------- budsgunshop.com/product_info.php/products_id/169764/lancer+l5g230blk+l5awm+gen+2+30rd+5.56+black ----------- Cheers and stay safe!