To expand on what Klaus said, sampling a 100MHz sine wave with 200MHz could conceivably give you an output of 0V DC. So then it doesn't matter WHICH solution you use.
At exactly Nyquist you could do as well with a 1-bit
DAC (inverter / buffer).
At lower frequencies you say nothing about desired
accuracy.
A post-sampling could eliminate some spurs that
may come from not-ideally-aligned inputs causing
a non-monotonic transition from "code N" to
"code N+1" as elements of the DAC reswitch.
But you ask for DAC and then talk ADC mostly.
What's the real interest and some idea of real
requirements?