You might find this review interesting... https://www.youtube.com/watch?v=J_LzV45Ha30
The reviewer says that the Teac has poor speed stability, so it suits best for rock/pop not classical music or other records with longer notes. For this money the Pro-Ject featured in the review is good sounding and better than the Teac (neither the Denon or Fluance was featured in this review). If you like the brand Teac I would recommend going for a more expensive one like the TN550, this has clearly a better drive system.
The Denon has good sound for the money, the stereo image or sound perspective is a bit shrinked compared to more expensive turntables and the sound is lacking a bit in details, but for the money it's perfectly Ok and if you want automatics then this is a nice turntable that's been around for quite some time on the market.
I can't comment on the Fluance RT81, I don't know anything about it. It looks like a combination of parts used in Audio Technica turntables, but with a nice plinth. Price is suspiciously low. Question mark for speed stability.