for melee, definitely the spiders on lvl 3 of the SoS. Most people use the large room at the beginning of the floor, but there is a less known, more concentrated room nearer to the back. check out tip.it's map of the SoS to find it. I'm lvl 94 f2p and i get around 30k exp per inventory of tuna with str pots. not sure the xp/hr rate. happy training!