I like to see stock clouds in 1.12 ...not everyone is keen on fiddling with Mods and waiting for their compatibility to newer ksp-versions. Especially for console players who can't install mods, clouds would be an optical enrichment.
And another thing for 1.12 I like to see are station parts - make space stations a real thing and give them a usefull purpose. Give us things to do up there, which can only be done in a space station.
Also Iike to see bigger commandpods. E.g. a crew capsule with 5 or more kerbals or some part ideals from the near future series implemented in stock.