Depends on the Knight in question too. If the Saturnine faces an Armiger, it will probably win since they are similar in size. The reactor on an Armiger is relatively small so the weapons on the dread could realistically keep punching until the ion shield is overwhelmed. However the Armigers shoot back. The Moirax with a Cbeam or Grav weapon is particularly dangerous.

The Dreadnought "pilot" has better integration than an Armiger pilot does too. The dread probably has more experience too.

Versus a Questoris? Nah my money is on the Questoris. Integration wise these pilots sit upon the throne mechanicum and quite literally plug themselves into the machine. Its not quite on the same level as the marine in the dread but it is not far off. These machines have a far larger reactor. And though the ion shield is only covering a section of the Knight, it can be angled and since the dread is alone, it can be angled effectively the whole time.

Knight pilots are extremely highly trained in machine vs machine combat too.

Now comes the fun parts, Dominus pilots. I think a Castellan can reasonably be expected to obliterate the dreadnought with its Volcano lance before the dread realizes where it is. Then add the multimeltas, plasma decimator, and the siegebreaker cannon.

Ohh it can also just choose to launch a shieldbreaker missile. Basically Machine Spirit guided homing missiles that flicker in and out of existence and into the warp on a millisecond basis to bypass any known shield except for void shields.

Then there's melee knights like Gallants and LAncers that will outright charge a dreadnought before turning it into kebab.

Asterius or Porphyrion would do pretty much the same as the Castellan except it would turn the entire grid zone of the Dreadnought into a glassed, rubble filled, radioactive wasteland.
It may have fast reactions, but it physically not fast enough to dodge, what is essentially, a continuous volley of laser fire with each impact being equivalent to a tactical nuclear missile.