Red Dot/Green Dot
My Walther had an older Burris red dot with manual on/off switch, which I keep forgetting to flip so I replaced it with a SwampFox Justice closeout with green dot and shake-awake. It seemed fine indoors but wasn't up to bright sunlight, so I ordered a newer Bushnell RXS-250 for slightly more money. Here's a side-by-side comparison...
I'll probably mount the SwampFox on something I don't shoot much.
I really like the field-of-fire around my house. I don't have to worry about hitting any of my neighbors for 150 ft and even then, it's only two houses.