Hey OP you definitely made the right choice the AT2020USB+ is a AT2020 with a USB interface built into it while the ATR2500x is technically a "budget" option (however on the used market it doesn't surprise me that its more expensive due to it being newer)
As far as pure technical specs go the AT2020USB is better in the areas that matter
The frequency response of the AT2020USB blows the ATR2500X out of the damn water AT2020USB+: 20hz to 20Khz (the range most people can hear) ATR2500x: 30hz to 15Khz
To clarify this while the cut to the lower bass (20hz vs 30hz) wouldn't affect to tone of the mics the treble frequencies missing would (15Khz vs 20Khz) This makes the ATR2500x sound less "open"
The tonality of the microphones is also significantly different The AT2020USB has the "Audio-Technica Sound" which is a very detailed, modern sound, it can sometimes be a little bit grainy (certain words come out slightly over processed) but its a nice sound signature.
The ATR2500x has a "budget" sound it's very mid-forward emphasizing the 'nasal' frequencies, due to the lack of a upper treble region and a rough EQ it can also tend to sound like you're in a box (street term is literally 'boxy' lol)
The areas where the ATR2500x have the advantage is mostly in the technology side For instance as you noticed it is USB Type C instead of an A-B USB It also has the ability to record in 24 bit, 192 Khz (if you're a gamer this would be the equivalent of 1440p144fps)
Overall OP your choice between the 2 was the right one, I understand why you'd want of a USB mic over XLR and to be honest, USB mics have come a VERY long way, I do want to throw a recommendation for a USB mic that I personally believe is better than the AT2020USB and ATR2500x Thats the RODE NT-USB (the regular not the mini) since it has a more natural smooth sound signature to it
Here's a link if you're interested https://www.amazon.com/dp/B00KQPGRRE/ref=cm_sw_r_apan_glt_fabc_X2MAXDE4CFCWM059SJVV