Streaming: WiFi or wired??

(1) When possible, do wired.   With few exceptions, in most cases wired will do better than wireless.  
(2) You haven't mentioned a budget.  If this is your entry into streaming, then a Bluesound Node 2i (retails for $550) is a good place to start.          Blu OS is a nice interface.  And it's good value for the money.  

A wired connection will always provide the best connection.  

I'm curious about this "wired always best" attitude. What if someone (like me for example) obtains his or her internet wirelessly to begin with. Is my streaming signal already compromised? 

Or would the wired ethernet still be advantageous coming out of my modem as opposed to wireless?

I'm using a Bluenote Node 2 that somebody miracled me wirelessly and it (including its internal DAC) sounds pretty damn good streaming www.kfjc.org or www.archive.org content.

There’s nothing compromised about wireless if the signal is strong and you’re not using some kind of lossy compression (mpg, Blutooth). Given that, wired or wireless might be slightly better, depending on the quality of implementation in the particular device.

(This is similar to the question of whether USB or SPDIF is better. The answer is the same: it depends on the implementation.)

Audiophiles tend to make hard-and-fast rules about things that are not all that clear. My hard-and-fast rule is, ignore such rules unless there are real data to back them up. Real data does not mean one or a few guys listening to one or a few pieces of equipment and generalizing from there.

I suggest you use whatever is most convenient for you. Happy listening!

The following thread will be of interest:

https://forum.audiogon.com/discussions/better-sound-with-ethernet-cable

The bottom line to my three lengthy posts in that thread is that I agree with what @mike_in_nc said in his post above.

Regards,
-- Al