svgcleaner looks not to support any lossy compression at this stage. Granted, svgo’s lossy compression is very pathetic, but for many images it will have enormous impact. (I say very pathetic, because it’s pretty much just rounding of numbers to N decimal places—no awareness of perception or how different scales may mean that one decimal place means radically different things in different parts of the image, no path simplifications using Visvalingam-Whyatt or similar, &c.)

Being focused on theoretically lossless compression techniques, svgcleaner’s GUI doesn’t look to include rendering of the SVG, and focuses on batch operation. For svgo there is Jake Archibald’s SVGOMG which renders the SVG and so lets you see what the impact of the lossy compression employed.

After fighting with the options, failing to find a good default, and still consistently getting larger images, I fail to see how svgcleaner is better.

I think it's only with lossless compression that it's better.

svgo has a gui online called SVGOMG.