i mean, i think there's a difference at taking someone who is naturally good at something, and playing that jungler to their strengths.
You don't take Lee Sin and farm: you gank.
You don't take Fiddle/WW/Nunu and ignore dragon: you slay it.
However, let's say you decide to do some silly runes + masteries (flat AP reds, flat AS blues, flat HP quints) to take dragon at the 3:00 mark "every time". Well now rather than playing towards your strengths, you are 'cheesing' and really doubling-down on them. If your plan doesn't go 100% perfect, you are quite likely going to be a liability because of it.
You just have to make sure whatever you want to do is... actually good in the meta? When Feral Flare was released, you better have been playing an Autoattack Farmer. Season 2, you better have been playing a level 3 ganker. It's hard to say exactly where the optimal gank/farm/objective combination lies.
The gold values for the 8% AP/AD in the earlyish/midgame is something like... (i am going to sort of assume both teams will kill dragon once in 25 minutes, so i'm focusing on the gold value for the 15-20 minute mark).
550-600 for the ADC early game (assuming they go BFS - trinity carries get less AD, but more AP so it's probably about equal)
220 for the AP early game (assuming they are going Athenes or Tear + Morellos. DFG rushers who are fed and start off with an NLR will get about 400g).
Basically nothing for the support.
Junglers get ~200 gold in terms of clearing power. Once they finish their AD/AP item, they get another ~200 gold for ganking/teamfights.
2x Dorans + Brutalizer AD top laners get ~500 gold - pretty huge. AP tops who go RoA will only get ~200 gold.
So the first bonus is significantly better for the ADC, aggressive AD top laners, and AD/AP carry junglers once they finish their item (which actually means fast barons are LESS useful for Nunu since he is probably going the HP item right?).
Traditional mages would probably prefer the 200 gold for their completed item early-game, but once they have 2-3 items, the 8% AP is really nice. Assassins/Ahri/Syndra prefer the new dragon buff. Supports pretty much LOSE 100 gold (spend 100 on a pink, and they get nothing out of it). AP tops would probably prefer the 200 gold since they have to wait for Tear/RoA to stack anyway.
+15% damage to minions/monsters... hard to put a value on that. i suppose it is kind of like an old Machete? Without any of the regen. So that's worth like 150 gold max, except for the jungler. The real value of the 2nd dragon is denying the enemy their first buff.
+5% MS is a weak pair of tier 1 boots. Jungles who go Mobo get a little bit more of a benefit, but generally ~15 MS. So that's worth ~200. A lot of people would still prefer that 200 gold to go to a completed items. However, the %MS does help you close games since it allows you to initiate slightly easier.
+15% damage to turrets. Not very useful if you are WAY ahead (not many turrets to kill). Pretty useful in a close game if you're a siege comp, though. At the very least, it's worth ~900 gold (a pickaxe) on your ADC whenever they are shooting a tower.