Agreed with most of the above especiall the comment regarding profoto mono's they are not all that great IMO. The flash tubes are mounted in different positions than profoto heads making the effect of some diffusers different ( eg beauty dish ) and they dont pack as much punch as they advertise. Elinchrome make the best in biz mono heads in my expreience PLUS you can use their uber cool software to control the individual head power levels through your computer making awkward or elevated lights easier to adjust.
I do prefer the profoto pack/head system the best over the others. Lots of support wherever you go. Tough, light, consistent pops and stable color temps especially over time. Speedo float like mad in this regard but they are tough as nails and will last forever.