All previous generations of the galaxy phones I have had have terrible audio recording performance in loud environments like at a concert.
It wasn't clear whether you were looking for an audio app or a video app that has good audio performance as well. I'm sure that both exist, but I'll concentrate on the S5 audio since I rarely use the S5 for video myself.
Most android audio recording apps aim for ease of use. And as you've observed with decidedly mediocre performance. But the S5 is capable of results every bit the equal of IOS if you are careful in your selection of apps. The native UI still doesn't provide for auto gain, but you can add this capability with a recording app such as RecForge Pro.
The S5 has a secondary, noise canceling mic that can be set to operate in a directional pattern with good results. Better still would be using a higher quality, external directional mic, typically connected through the TRRS jack.
For the overachieving recording engineer, the ultimate approach is to use an outboard USB interface e.g. a Focusrite Forte or 2i2, with outboard ADC and preamps. This is a vast improvement over the dismal S5 ADC. The Forte for example has 192 Khz, 24 bit ADC conversion as well as decent mic preamps and XLR as well as TRS inputs.
An app like Audio Evolution Pro supports the USB interface and offers comprehensive soundboard controls e.g. level /EQ /mixing, et cetera as well as a non destructive, non linear editing suite.
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