So I have an NVidia Shield on my main TV in the house, the rest have Roku players and my wife is getting annoyed with the fact that many of her files on her External Drive or USB flash drives can't be played on the Roku's. So looking to replace the Roku's with Android TV devices but don't really want to pay $200 each. What are the best Android TV options with USB playback that aren't too bad on pricing.
I'm thinking that you are pretty much in a lose-lose situation, because your wife is going to end up comparing the NVidia Shield's performance to any Android TV box that you end up buying, so you would probably be best off just buying NVidia Shields to replace the Roku players.
The other option would be to convert the media that won't play on Roku, which are most likely .avi or files that have videos in them encoded using DIVX/XVID, which are not supported on Roku players.
If the issue is with files that are encoded using h or x265 (HVEC) then the Roku player apparently needs to be one that supports 4k.
I use a Roku Ultra (4640) and it plays pretty much everything except .avi (DIVX/XVID) media, and to play those I either convert them using "FormatFactory", I play them on my Mi-Box 3 using VLC or play them using an old Sony Media player.
With file conversion being the option I usually take, because once, the file is "converted" the file can be played at any time on the Roku without any issues.
Not sure if this is what you were wanting to hear, but I do hope that this made sense and was helpful.
Best wishes and good luck!