At some power outputs THD+N is actually lower in BTL than stereo:

View attachment 198024
Which amp with this power output can compete?

I guess it depends on what you care about.

In all cases BTL has higher noise than stereo. You can see this by looking at lower power output where THD+N is dominated by N.

8 ohm - stereo: 1 W THD+N = 0.0012% (-98 dB), residual noise = sqrt(1 x 8) x (0.0012/100) = 34 uV

8 ohm - BTL: 1 W in to 8 ohm THD +N = 0.0025% (-92 dB), residual noise = sqrt(1 x 8) x (0.0025/100) = 71 uV

4 ohm - stereo: 1 W THD+N = 0.0019% (-94 dB), residual noise = sqrt(1 x 4) x (0.0019/100) = 38 uV

4 ohm - BTL: 1 W THD+N = 0.004% (-88 dB), residual noise = sqrt(1 x 4) x (0.004/100) = 80 uV

I personally care a lot about noise because unlike distortion it is always present.

The other issue with noise is that the BTL nominal gain is 31.5 dB compared to 25.5 dB for stereo. This means that with BTL upstream noise from your source will be multiplied by double compared to stereo.

I will admit that for 8 ohm loads THD+N from 30+ W is a bit better for BTL, however the opposite is true for 4 ohm loads. Overall this region of the THD+N plot does not worry me much as at higher power levels distortion from your speakers will certain dominate compare to distortion from your amplifier especially when that amplifier distortion is in the 0.001-0.002% range.

Michael