I use the codec packages from RPM Fusion so I don't mind using AAC audio...

You can see what all formats are available using a random video link:

[youtube] 9dhmS237wsw: Downloading webpage
[youtube] 9dhmS237wsw: Downloading video info webpage
[youtube] 9dhmS237wsw: Extracting video information
WARNING: unable to extract uploader nickname
[youtube] 9dhmS237wsw: Downloading MPD manifest
[info] Available formats for 9dhmS237wsw:
format code  extension  resolution note
139          m4a        audio only DASH audio   49k , m4a_dash container, mp4a.40.5@ 48k (22050Hz)
249          webm       audio only DASH audio   55k , opus @ 50k, 4.62MiB
250          webm       audio only DASH audio   78k , opus @ 70k, 6.41MiB
140          m4a        audio only DASH audio  128k , m4a_dash container, mp4a.40.2@128k (44100Hz)
171          webm       audio only DASH audio  135k , vorbis@128k, 11.08MiB
251          webm       audio only DASH audio  168k , opus @160k, 12.51MiB
278          webm       256x144    144p  110k , webm container, vp9, 30fps, video only, 6.38MiB
160          mp4        256x144    DASH video  118k , avc1.4d400c, 30fps, video only
242          webm       426x240    240p  237k , vp9, 30fps, video only, 8.92MiB
133          mp4        426x240    DASH video  259k , avc1.4d4015, 30fps, video only
134          mp4        640x360    DASH video  370k , avc1.4d401e, 30fps, video only
243          webm       640x360    360p  417k , vp9, 30fps, video only, 17.01MiB
135          mp4        854x480    DASH video  674k , avc1.4d401f, 30fps, video only
244          webm       854x480    480p  708k , vp9, 30fps, video only, 27.83MiB
136          mp4        1280x720   720p 1199k , avc1.4d401f, 30fps, video only, 69.77MiB
247          webm       1280x720   720p 1364k , vp9, 30fps, video only, 59.11MiB
302          webm       1280x720   720p60 2029k , vp9, 60fps, video only, 85.29MiB
298          mp4        1280x720   DASH video 2264k , avc1.4d4020, 60fps, video only
137          mp4        1920x1080  1080p 2294k , avc1.640028, 30fps, video only, 134.18MiB
248          webm       1920x1080  1080p 2566k , vp9, 30fps, video only, 137.01MiB
299          mp4        1920x1080  DASH video 3934k , avc1.64002a, 60fps, video only
303          webm       1920x1080  1080p60 4032k , vp9, 60fps, video only, 231.51MiB
17           3gp        176x144    small , mp4v.20.3, mp4a.40.2@ 24k
36           3gp        320x180    small , mp4v.20.3, mp4a.40.2
43           webm       640x360    medium , vp8.0, vorbis@128k
18           mp4        640x360    medium , avc1.42001E, mp4a.40.2@ 96k
22           mp4        1280x720   hd720 , avc1.64001F, mp4a.40.2@192k (best)

Then you can do something like this to set your preferences:

$ youtube-dl -f <video_num>+<audio_num> <link>

IIRC you can use commas between numbers in order of your preference, something like:

$ youtube-dl -f 137,298,135+140,139 <link>

$ youtube-dl -f 137,298,135+140,139 https://www.youtube.com/watch?v=9dhmS237wsw
[youtube] 9dhmS237wsw: Downloading webpage
[youtube] 9dhmS237wsw: Downloading video info webpage
[youtube] 9dhmS237wsw: Extracting video information
WARNING: unable to extract uploader nickname
[youtube] 9dhmS237wsw: Downloading MPD manifest
[info] 9dhmS237wsw: downloading video in 4 formats
[download] Destination: UniFi Guest WiFi-9dhmS237wsw.mp4
[download] 100% of 134.18MiB in 00:13
[download] UniFi Guest WiFi-9dhmS237wsw.mp4 has already been downloaded
[download] 100% of 134.18MiB
[download] UniFi Guest WiFi-9dhmS237wsw.mp4 has already been downloaded and merged
[dashsegments] Total fragments: 77
[download] Destination: UniFi Guest WiFi-9dhmS237wsw.m4a
[download] 100% of 4.27MiB in 00:11
[ffmpeg] Correcting container in "UniFi Guest WiFi-9dhmS237wsw.m4a"

Thanks,
Richard