The best replacement for sketchup is sketchup pro.

The best alternatives to sketchup are rated as following:
★★★★★  sketchup pro
★★★★★  autocad
★★★★  blender
★★★★  revit
★★★  solidworks
★★  rhino
★  cad
★  google sketchup
★  3ds max
★  sketchup make
★  3d max
★  chief architect
★  123d
★  freecad
  tinkercad
  archicad
  trimble sketchup
  vectorworks
  autodesk
  formz
  sketchlist
  turbocad

Your alternative for sketchup is not listed? Suggest!
Speaking about sketchup, one probably shouldn't forget about vray.

Other search terms related to sketchup and their ratings are:
★★★★★ vray
★★★ google earth
★★ dimensions
★ kerkythea
★ wacom
★ lumion
★ garden design
★ magic mouse
render
cad
You have in mind a companion for sketchup and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of sketchup in all years. Click on graph for more.
sketchup
sketchup pro
autocad