I don't think I could ever go singlespeed!
They are hard work when hills are involved, true! Fun on flatter roads though, and on
short climbs at no more than, say, 6-7%.
I ended up making mine into an unusual 1x6 mullet - a bar-end shifter on the left side of the handlebar because I had fitted a mirror on the right, and a DIY 6-speed cassette. I still ride it mainly in the original singlespeed gear but can now venture into hillier terrain if I want to.
I like the 1x11 bike that I have in Devon. That has a 42/42 bottom gear which is okay on 15%, a slog on 20%, but has so far failed to let me get up 25%. I don't tackle very many 25% climbs so I will probably leave the gears alone, but maybe if/when the cassette needs replacing I might investigate an 11-46 replacement. Alternatively, a 38 or 40 tooth chainring to replace the 42, though that would give me a pretty low top gear of only 38/11 or 40/11.