I always got my best gain with 300 Ohm flat wire cable, and resent the day it started going to 75 Ohm coax. More interference, but more signal, too.
I have never found an RF amplifier that did much for the signal. Back in the pre-cable days, my father employed a device from Jerrold known as a trap, which was used to improve weak signals close to strong ones. In our case, Channel 8 (WNHC-ABC, New Haven) was overpowering channel 9 (WOR-Ind, New York) and Channel 7 (WABC-ABC, New York). That sometimes worked depending on atmospheric conditions, but it didn’t really strengthen the signal, only made the existing signal more useable.
I guess 75 ohm became more prevalent with the increase in interference sources...
At my parents we had a close & strong FM station that wreaked havoc with other FM signals and trying to get a distant VHF Channel 6 station that was right in line with that FM station. I knew the engineer for that strong FM station and he made us a custom notch filter to knock down his own station. :-)