For my ARs and shotguns I have VCAS slings and the former Ares Armor Huskey Slings, which is basically an improved VCAS with more slick webbing, making the slider easier to manipulate. Got them when Ares was still in business, before all the BS went down.
My AK uses a Chinese Type 56 sling, old school durable cotton canvas that does the job at a low price! I get mine directly from China
I hated the USGI parade slings on issued M16s and M4s but I found they work great on my M1903 and M1903A3. Best of all the slings were free too lol