This comes up every time this sort of thing is discussed on HN. Sustained 1 g acceleration takes a staggering amount of fuel, and carrying enough to slow down again makes it even worse.
That's exactly the point. The limiting factor to space travel is how to achieve acceleration, and not the acceleration limits of the human body.
It's definitely sci-fi for now, but we can always imagine some far out way to store energy much more densely than antimatter. A huge amount of photons orbiting a micro black hole on its Schwarzschild radius, would only weigh as much as the black hole and let you store a potentially infinite amount of energy.
No, they would have as much mass as the black hole plus the energy of the photons (they still distort spacetime and exert a gravitational force, and have inertial mass) and you still have to move that mass with you. You may have increased your fuel density, but you haven’t reduced its mass compared to antimattter, and you still have not dodged the relativistic rocket equation.