I can't comment on best value because that is subjective, by I can say I regularly carry up to 5 bikes on the roof at speed over distance and would not consider using anything other than Thule aero bars and bike carriers.
If you are using narrow MTB tyres (below 1.9") or road tyres then carry the front wheel separately on a wheel carrier as the handlebars will shimmy at speed otherwise.
I use Thule 591and 511 for MTB or recreational bikes, and Thule 561 for roadbikes, MTB with narrow tyres, or high speed. (requires separate wheel carrier).