Sigma-delta 1 bit sound more digital like ( more accurate )
Both have weaknesses. Digital conversion to analog is along two dimensions where errors can occur - amplitude and time.
R2R suffers from differential non linearity in the amplitude (bit levels) as well as susceptibility to jitter particularly at 44.1KHz. 1 bit Sigma Delta suffers from jitter (differential non-linearity in timing) but is highly linear in amplitude.
There are solutions.
1 bit Sigma Delta operating at 4xDSD is less likely to have much in the way of audible jitter (timing non-linearity) as the operating frequency and noise shaping is way outside the audible band.
Upsampling can help with an R2R DAC by “randomizing” amplitude non-linearity.
Latest Sabre DACs use 6 bit Sigma Delta DAC with a mathematical randomizer to help eliminate non-linearity. These latest DACs are a hybrid between traditional, R2R 16 bit DACs and 1 bit Sigma Delta - they have both great amplitude linearity and low jitter (timing issues).