Hi Leo,
Reading comfort is a difficult criteria because it depends a lot on how you read: sitting, one-handed, lying down, two-handed, etc.
That being said, I think it's safe to say both of those Kindles are very comfortable in most circumstances. One-handed reading is easier on the Oasis (without the cover) because of its light build and weight distribution, but its asymmetry requires flipping to switch hands. No such requirement on the Voyage.
They both have some sort of physical button for page turns for those who love that, but I actually find the Voyage's preferable because it's harder to press them accidentally. Sometimes, reading on the Oasis, if you rest your thumb on the button and use it to counter-balance the weight of the other side, you end up pressing the button inadvertently. If you support the weight with your other fingers from behind then this isn't an issue, more just something to get used to.
The Voyage with case is the best e-reader for lying down, I find—flip that origami case around and it props up perfectly on either side without any precarious tent-like arrangements using normal book-type covers.
The front light on both is bright and sufficiently customizable. The Voyage's will auto-adjust if you want it to, but I prefer to handle that manually. On my units, the Voyage has more even light distribution than the Oasis, but that can easily vary from unit to unit.
Hopefully that answers your question but feel free to follow up with more specifics pertaining to your reading habits.
