For initial climb speed it depends on what you are trying to achieve.
If there is a terrain/obstacle the best angle is the speed that you want until you are above it and at a safe height. As an example one might wish to climb at Vx until above MSA/LSALT-good airmanship! Best angle is also best to use until you are pointing the aircraft in the direction of outbound track. Vx will get you over a line of weather, whereas Vy might climb you through the cloud tops.
The best RoC , Vy, will get you above conflicting traffic quicker (not all the time, Vx may be more appropriate in some instances) and into tail-winds quicker. If you are climbing into a head wind, you might want to consider a cruise climb speed that is greater than Vy as best rate will just climb you into an increasing head-wind.
What Fokker12 said
