For an all-around lens where f/1.4 is not important, I have and use my V3 Summicron. This is the black one without the focus tab, catalog number 11817. I reach for it most of the time. When I want more atmosphere, I use my V1, the collapsible. For great black and white performance, I use my Dual-Range Summicron; but as an all-around lens, it is a bit heavy.
I have the version 2 Summilux, but it seldom occurs to me to use it, as it is heavier and larger, and I haven't been shooting in low light for quite a while now. It's on my to-do list to get it out and do some shooting with it!
For optical quality, enough speed, and small size, I like my V3 Summicron and my collapsible Summicron about equally. You can't go too far wrong with a Summicron!