At 44.1 kHz sampling, filter 6 has the flattest and smoothest frequency response, and flat phase response. It measures identical to filter 7. However, filter 6 does not fully attenuate until 24.1 kHz, so it can leak some HF noise that could alias, but any aliasing would be above 20 kHz which should be benign.
Filter 2 is the flattest filter (both in frequency response, and in phase) that fully attenuates by 22.05, so there is no HF noise or aliasing. But Filter 2 is not quite as flat as 6, nor quite as smooth. However, Filter 2 is pretty darn flat and smooth, only -1.5 dB @ 20 kHz and its ripple is less than 0.1 dB.
IMO, filters 2 and 6 are equal candidates for the "best" most correct & transparent filter. They just make slightly different tradeoffs. These tradeoffs should not be audible, so which to pick depends on what you think is the worse evil.
PS: Filter 3 is one of the "worst", with significant attenuation below 20 kHz and non-flat phase response. If you prefer a minimum phase filter for whatever reason, then filter 4 is the best of that type.