What is Reddit's opinion of Super Antenna MS135 SuperWire Stealth Bulk 135 feet Wire #18 Stranded ham Radio Amateur PTFE?

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I've had good luck with 16ga copper clad aluminum speaker wire, but there are some purpose built wire bundles you can get like this.

https://www.amazon.com/gp/product/B014ZT3BA2

As for builds that is a whole rabbit hole on its own, and before you just go building something you should try to identify what you want to listen to first as the antenna should be tailored to the task as much as possible. I tend to use a random length wire antenna around 84' in length, but that is more for ham radio specific RX. I also have a random old TV dipole that I chopped the leads off and wired straight into the balun that works with mixed results. Another antenna I've had pretty good luck with is a cheap Chinesium mini whip, but that isn't using the balun, you really need to be able to get it up in the air, and you can't TX on that or you risk damaging it.

Maybe check out /r/AntennaDesign, and give the below docs a read if you can find them somewhere. Hint it rhymes with moogle.

USMC Antenna Construction and Propagation of Radio Waves

The ARRL Antenna Handbook

ARRL Basic Antennas

Finally go read around what other ham radio and SDR nerds have done. The SDR is really just the enabling device, now you get to go collect signals and getting a good antenna for the task you're trying to accomplish is the next step to getting a good read on otherwise hard to capture signals.

Also not to disparage the HackRF, but its really not a great device for digging out weak signals. You can do a lot with it, but its a hacking tool first and foremost. If you desire is to listen then there are lots of other SDRs better suited to that task. Not that you can't do it with the HackRF, I had been using it successfully for quite some time before grabbing a different SDR for my primary listening device.

I went with this stuff

Super Antenna MS135 SuperWire Stealth Bulk 135 feet Wire #18 Stranded ham Radio Amateur PTFE https://smile.amazon.com/dp/B014ZT3BA2/ref=cm_sw_r_cp_api_glt_fabc_A1ADTQDD97R10PK50E92?_encoding=UTF8&psc=1

But from what I can tell any copper wire will work fine. Some people on YouTube are running 26 gauge stuff.