I have also experienced the age-related decrease in near-vision, complete with about 15-20 pairs of reading glasses laying on every horizontal surface in every room of my house. It gets even worse as my contact lens prescription for near-sightedness has increased slowly over time. I noticed a few years ago that the aiming dots were getting harder and harder to visualize against the target black, particularly in the early AM or on cloudy days. So I did a comparison of the reticle aiming dots using three different scopes I own: Nightforce Competition with FC/D reticle, Nightforce NXS 12-42x56 with NP-2DD reticle, and an IOR-Valdada 36X BR with a floating dot reticle.
Because the IOR-Valdada is a fixed 36X scope, I set the other two as close as I could get to 36X. The relative angular subtensions of each aiming dot at ~36X calculate to 0.125 MOA (IOR-Valdada), 0.116 MOA (12-42 NXS), and 0.106 MOA (Competition). Not surprisingly, my ability to easily see the aiming dots against the target black under moderate to low-light conditions was directly proportional to their angular subtension. The Comp aiming dot (0.106 MOA) is almost impossible for me to see well, even in good light. I struggle a bit at times with the NXS dot (0.116 MOA), particularly in low light. However, it usually works ok The 0.125 MOA dot of the IOR-Valdada is pretty much "in your face" easy for me to see under all conditions I have used it so far. Notably, it is nowhere near large enough to cause any issues such as occluding too much of the X-ring/target face. The X-ring is basically 0.5 MOA, so there's plenty of room to play with in terms of reticle dot subtension.
The main concern about this type of vision issue is that it will typically only get worse over time. So you might want to think ahead a bit. For example, the 0.125 MOA dot is working well for me right now, but will that be true in 5-10 years? I don't know. But I have strongly considered picking up a couple March scopes due to the fact they offer aiming dots even larger than 0.125 MOA. As Denys posted above, I think the MTR-5 reticle would be just about perfect for me. However, if at all possible, you will want to look through a few different scopes to get a better idea of what will satisfy your vision requirements. I would not be concerned about going with an even larger aiming dot in terms of occluding part of the target. Realistically, it's just not a concern for an F-Class target with the aiming dot sizes we're talking about.