I use the Sigma 24-70mm f/2.8 Art lens for a general purpose, single lens option. I owned the 24-90mm Leica at the same time and, other than the extra 20mm on the long end, could barely see a difference in image quality, even comparing side by side shots. This was on the SL2-S, by the way.
The Sigma is significantly lighter and a fair bit smaller than the Leica lens, which is also very appealing. Add to that, the Sigma is a f/2.8 constant aperture, which is a bonus. Budget wasn't an issue, so I went with what worked best for me, handled well and produced the best images.