I think Jakob obviously is the better track runner of the two now whereas Jacob is the best on the roads.
On the track:
Jakob Jacob
1 Olympic gold 1 Olympic bronze
1 WC gold and 2 silver (including 1 indoor) 1 WC bronze
4 outdoor and 3 indoor EC gold +
1 indoor silver 2 Common Wealth gold
9x diamond league winner 1x diamond league winner
1 WR indoor 1500m
4 European records (1500m outdoors and
indoors, 2000m and 5000m)
1 U20 Worlds silver and 1 bronze 1 U20 Worlds silver
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Roads and X country:
Jakob Jacob
4 U20 X country golds and 1 senior 1 U20 X country gold and
gold at European Champs Senior silver WC
1 WC HM gold
1 WR and 1 African record in HM
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Who is the best overall runner?
The IAAF ranking has Jakob as no. 5 and Jacob as no. 39.
I also think Jakob at the moment must be considered the best overall. Jacob´s dominance on the HM can´t outweigh Jakob´s dominance on the 1500m and the 5000m (and possibly every distance in between).
But things can change. It would be interesting to see what happens if there were more fast paced races on the 3000m and 5000m with participation of all or most of the top runners, including the 2 Jac/kobs.
It should be possible next year where there is only one major international championship to focus on.