Which user-agent string is most optimal for use in ADM or similar download management applications?

I thoroughly comprehend **what** a user-agent string is, and **how** to spoof/parse them. What I can't seem to find in the endless sea of search results that all speak about the same two aforementioned points is: **which** should I use? For my use-case, it'd be specific to using [Advanced Download Manager & Torrent downloader (ADM)](https://play.google.com/store/apps/details?id=com.dv.adm) on an Android device for downloading videos. Which — if any — would be optimal in terms of file accessibility, speed, stability, etc? Which should be avoided in the practical sense? I understand this is likely dependent upon the web developer's end, but in a more general sense I'm wondering if the UA has any inherent impact to these factors, if all else remains the same? EDIT: to clarify, from my observations the typical use cases seem qualitative — whether a particular file is served or not, i.e., true|false. I'm wanting to confirm there are no other functional impacts from the user's standpoint aside from whether a file is made available or not (disregarding build variants based on UA, so assuming for example's sake that they are identical).