I am the opposite - I'll have the feeling that I'm not going fast enough when I don't know how fast exactly I am going. Or if it feels fast enough, I'm curious to see if it really is faster than usual

That said, I've had good experience with wired Sigma units - had two older models, both outlived the bikes they were on. Currently have a wireless Force WLS 12 (Czech brand but I suspect a lot of their products are rebranded generic Chinese stuff as I have seen identical or very similar products online under various other names; this one looks very similar to the InBike unit mentioned above), bought for 17 euros, although it seems to have died just a few days ago - changing batteries and readjusting the distances didn't help, seems to get no signal from the sensor. It worked for 2 years, didn't interfere with lights, although some other outside interference like electric city transport did affect it. Other than that it worked fine.