For utility modules, I'm really happy with my Shades which is a mixer, attenuverter, offsetter and my Kinks which combines an inverter/rectifier, a min/max and a noise/S&H.
If you take a look at most prebuilt systems by modular brands, they usually have those function included.
-- Martebar
shades and kinks are excellent modules (I have a kinks and 3 shades in my racks)
2hp VCA, Avert, and Trim. I never see 2hp mentioned much beyond their Pluck module, but for space saving I really like their utilities.
-- baltergeist
they were all the rage when they first came out - until people realised that they are a pain in the ass to use because they are too small and fiddly - I have 2 trims (and a couple of others TM and tune, that I don't really use any more - maybe in the future for a small portable rack - or as additional sequencing) - one each side of clouds and they are great for that - set and forget - but playability wise big knobs rule!! which means bigger modules (the same can also be said about the erica pico modules - they are kind of worse though as they are an odd size, which is annoying)
My top utilities - Kinks, matrix mixer, stages, maths, shades, doepfer sequential switch
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities