Ethernet to SPF converters. What's your experience?

Thank you for all of the suggestions. 

I’m very familiar with the sound when connected directly from router to streamer via ethernet.  I’ve had it that way for a while. I bought the switch a couple of weeks ago.  So far, I like the sound with it.  I’ve only spent a few hours with the ethernet to fiber converter.  Jury is still out on that.  The little wall wart is plugged into the same power conditioner as my other gear, so that might be a problem.  I’ll look into that.

@boulder_bob Yes, the LHY ock-2 clock has three outputs for square wave and three for sine wave (I’m using square wave).  "more relaxed" is kinda what I’m hearing with the converter, but I’m not sure if I prefer that.  I need to do more listening. 

I have two systems on fiber. Both use switches with built in SFP fiber ports and both my streamers accept SFP fiber inputs. Definitely a lower noise floor. Before all that I tried those 2-piece ethernet to fiber converters, but too many connections nearly erased all the noise stripping that fiber does. So I bought the switches and streamers that had them natively. Much better. Lower the noise floor, blacker background = better more detailed audio. Btw, the AOC SFP modules are the best. 

Yes definitely isolate the wallwart from audio. 

I’m running Nucleus One and a basic Trendnet Switch. Nucleus is plugged into a dedicated circuit 1, system (DAC and integrated) are on dedicated circuit 2. Switch is plugged into a completely different circuit. 
The Trendnet switch, to my surprise, smoothed out digital glare when used with Nucleus. I’m also running WireWorld Starlight 10 Twinax Ethernet cables from eero to switch and from switch to Nucleus. That was a very good improvement as well. The WW Ethernet cables are really good. 

Been using SFP's for years and will never go back. Only using quality converters from Edisoncreation and Sonore Optical Module Deluxe, with Afterdark LPS, 

Not all fmc created equal, I've had cheap generic, now use Sonore OpticalRendu which also serves streamer function, meaning Roon Endpoint. This separate from a much more expensive custom build streamer which now only does Roon Core duties. While this makes for more complex streaming chain, many have found two streamer setup preferable for Roon. I highly doubt on board fmc within routers or switches provides sound quality on par with dedicated high quality fmc. I'm also skeptical as to quality of stock fmc within streamers. SFP modules, also called transceivers are variable quality as well, I replaced stock with Finisar 1475 to good effect. Finally, quality of AC to these devices important as well, meaning quality lps, DC cables, power cable  and power conditioning to the lps. I've optimized every single component in streaming chain, it all matters. 

Aside the above, quality I2S implementation and connection to dac superior to usb input, this includes dacs with very nice usb boards. Replacing dac internal master clock with external clock can be nice upgrade.