I don't have experience with any of those specific products but as an owner of both Profoto (Acute) and Elinchrom (Ranger) I can speak in generalities. The modifier mounting system is much better on Profoto than on elinchrom, same goes for the light stand mounting. Elinchrom has a cheaper feel seeings how their heads are made of plastic. In my experience both systems are reliable and consistent. I use Elinchrom octaboxes on both systems.
The B1 is 500wS, the B2 is 250wS, and the ELB 400 is 423wS. They are all capable of full body portraits through a medium/large soft box in a studio setting. They are also all capable of overpowering midday sun in some way or another but this is very much dependent on what modifier you are using and your subject size/distance, obviously the higher the light output the better in this regard.
For example: The B2 should over power the sun shooting headshots through a small/medium softbox, or perhaps full body shots with a standard 7" reflector or something similar, but the B1 and ELB are the only ones that stand a chance at over powering the sun for a full body portrait through a medium/large softbox, and I think that is pushing it. If memory serves I'm usually around 700wS-1200wS when I'm using larger modifiers outside in bright sunlight. It just depends on how much light the modifier transmits and the distance/size of your subject.
Seeings how the price of each is similar of these options I would with out question go for the Profoto B1.
