The Holosun 503G or GU, and 515C are both excellent. The solar cell is not to power it with no battery, but
rather auto adjusts brightness for lighting conditions. If that is not your cuppa tea, you can switch it to
"manual mode" and set it as you wish, like the 503G.
What I like most about the G and GU is the ease of changing the battery, under a cap on the right side. On
the other hand, with the very long life, auto shut off, auto awake, that is really a non-issue. Change the
battery every two years and you are GTG.
The 515C has the QD base, lens covers, and "kill flash", as well as the solar cell for auto brightness. So far
I have not needed to override the auto brightness setting.
I replaced Eotech 552's and 512's with the Holosuns, which at least hold zero, a problem I had with all of
my Eotechs (I had four plus a Bushnell version at one time). I'm happy with the Holosuns.