"Better" depends on the rest of the sketch, but in most situations the second will be the more reliable one. Please note that the two sketches don't produce the same output, though. The second one will generate 2048 positons for one turn (you check the rising and falling edge) and therefore will have values for half a circle only.
Serial.println (encoder0Pos, DEC);
That is a no-go. Putting something on the serial interface inside an interrupt handler is a very bad idea.