Basically, when training melee in RS3, you would follow this order : attack > strength > defence. The best thing to do is to keep your attack roughly ten levels higher than your strength and defence.
On the contrary, in OSRS, the ideal way of training melee would be to keep your STRENGTH ten levels higher than your attack and defence. Hence, the best melee training order in OSRS is : strength > attack > defence.
For example :
On Diana, I got 90 attack, 80 strength and 80 defence. Now I will work on 85 strength and defence before getting 99 attack.
On Nin, I was level 40 attack, 40 strength and 40 defence. Then I raised my strength up to level 50, and, afterwards, I reached 50 attack and 50 defence. Then again, I will work on 60 strength, before getting 60 attack and 60 defence. Another efficient option would be to get 60 strength, then 60 attack, then 65 strength, and eventually 60 defence... Well, you see how it works...