WINSINN 50mm Blower Fan 24V 5015... https://www.amazon.com/dp/B07DB7DLMM?ref=ppx_pop_mob_ap_share

These are what I’ve been using for parts cooling. I also use their dual ball bearing fans for hot end and mainboard cooling. Dual ball bearing carries a 24 hour duty rating. They don’t need a rest. My mainboard fan is also directly wired to the PSU so I can print PETG with no parts cooling and not have to worry about cooking my cpu. The color changing fans are cool, kinda gimmicky for me though. I had three fail in quick succession so I won’t go back for a while. The one I’ve currently got on my hot end has been there for about 10 months. Same for the cpu cooling.

I went with these. Of the cheap brands, Winnsinn is supposedly one of the better ones. At less than twenty bucks for a four pack, not really much to lose.

I'm only using one at a time in my current configuration (BiQu H2 extruder/hot end combo), but I do have plans to go with two at a time in the future. I'm pretty happy with how noisy it is, and the hurricane of wind it produces is darn near impressive; I've had to turn down my part cooling to 70% when printing PLA+ at "normal" speeds.

Edit: Note on the Amazon page that there is an option to select different wire lengths. You'll probably land on the short wire lead length option, as I believe that is the default for that page. You will see an option for one meter length wire leads, though, if that's something you'd want. I ended up putting JST-XH connectors on the ends of my fan leads for easy change outs in case the Winnsinn fans didn't live up to expectations.

These are the fans I'm using: https://www.amazon.com/gp/product/B07DB7DLMM/ https://www.amazon.com/gp/product/B07DB5H6K1/ Along with the fan ducts and stuff talked about here: https://www.youtube.com/watch?v=dbS9MA4UkZA&t=1633s