The 787 has a shallow takeoff angle compared to other aircraft being an aircraft that sits quite low to the ground. A 787 will have an initial takeoff angle of 10’ max. Only once its cleared the ground will it pitch up further.
For the 787-8 and -9, weight depending and runway length, etc. I’ll use Flaps 5 for most of my departures. Throttle position of 70-74 gets you into the 90% N1 range which will be more than enough for most weights. For the 787-10 I found that Flap 15 reduces the chance for tail strike and also Flap 5 significantly has a longer roll sometimes due to a slower rotation for the length of the -10’s fuselage. Flap 15 will offer easier rotation on the -10 and less runway needed, but more drag. Hope that helps!