Which device makes for a better digital music source? Computer or streamer?

I don't stream in my listening room.  Uncompressed flac or wav files are stored on a ssd in a small form factor i5 running Euphony Stylus OS. DAC is a Bifrost 2. I'd have to spend many thousands more in hopes for a marginal improvement with a dedicated server.  No desire at all. My configuration wouldn't be taken seriously here since my monetary investment in it isn't 30,000.00 or more.

I'd be surprised if anyone could tell the difference ... 

Using a Cambridge Audio CXN version 1.  Sound is as good or better than my NAD CD player.  I can connect my PC (HP laptop) to the CXN through a USB cable but I cannot tell the difference between that and streaming directly from the CXN. 

The OP's question is a bit complicated because the "computer" and the "streamer" functions can't be separated easily from all the other functions built into (or added to) each device. You may have to consider everything you want to accomplish in the context of your whole rig. For example, if you want to run digital signal processes (say, software like HQPlayer) then you'll likely need a full-function computer in the loop, Maybe you just like to tinker, in which case you can do a whole lot more with a computer tied in.

I have a BS Node 2, a Mac Mini, a sonicTransporter i9 music server, and a Matrix Element X (integrated streamer/DAC/pre). After experimenting with numerous configurations in the past ~2 years, I still switch around sometimes.  But the configuration I tend to prefer, for "serious" listening not background music, uses the Mac Mini running HQPlayer or BACCH4Mac with a USB connection to the Element X. On the other hand,  Qobuz HiRes tracks sound pretty darn good with a more direct ethernet connection to the Element X (and no full-function computer in the loop.)  There's something to be said for using as simple and direct a connection as possible. 

But do dedicated streamers necessarily sound better than a full-function computer, if all you want to do is stream Tidal/Qobuz with no DSP? I dunno for sure, but I doubt there's a very noticeable SQ difference.