well i would say ultimate green goblin, if it's when he was the size of a small house, if it's when he first appeared however, then hobgoblin, yeah demogob's got all those nifty hell powers but ......well hobgoblin kicked the piss out of him before demo died, and hobgoblin's stronger, more lethal etc....than green gob....and he has more experience fighting, killing etc...than ultimate green gobling so hobgoblin wins out overall.
oh yeah well as for demo,,,,during a multi comic crossover saga called the 'inferno" demons were being unleashed all over the earth by a higher demon being and it was up to earths mightest super heroes once again to stop the threat (this included the x-men, spiderman, hulk, f4, and dr. strange to name a few) , hobgoblin was sick of gettin his ass handed to him by spidey so he went to the demon leader asking for enough power to beat spidey and was granted it,,,however, the power he was granted was that of the demon that posessed him. As a possessed hobgoblin, he went crazy, he was under the beleif that he was brought upon the earth to extirminate all sinners and then eventually himself. This lead to a ton of fights with spidey and ghost rider, darkhawk, dr. strange, morbius, etc....a lot of the mystical marvel characters....eventually the host macendale found enough resolve to tear himself away from the demonic force. He become the regular old hobgob once again but the demonic force manifested into a tangible demon called demogoblin, demogoblin spent most of his time trying to hunt down hobgoblin, and even went to the lengths of resurrecting the dead spiderman doppelganger to help him in his quest to destroy all sinners,,,,,over his time on earth he also teamed up with venom, and carnage, after making a pact not to hunt macendale anymore, Macendale however got a new strength serum from kravens son and went seeking demo,,,,when demo found hobgob he told him he was sorry but now hobgob had to die,,,,after a long fight hobgoblin beat down demo and spiderman rather easily with his new found strength when the church they were fighting in was about to collapse demo attempted to hold up a falling piller so spiderman could save an innocent child, then the piller fell upon him and thus was the end of the demogoblin.
Anyway considering that with Kraven's serum Hobgoblin/Macendale was about Class 12 Tons or more, and possess enhanced reflexes, agility and stamina, (he put down Spider-Man easy) i can say that he could be the last standing goblin here, but Ultimate Goblin is very strong too, he can leap great distances, project plasma bolts and blasts, and is nearly fast as Spidey, Demogoblin can use hellfire yes but hey he was beat down by Deathlok in Maximum Carnage so i don't give him too much credit, the regular Green Goblin possess the same strenght of Spider-Man but is less durable and fast, anyway he possess all his goblin gadgets, that would work well on all his opponents, anyway Osborn is too much megalomaniac to be a real threat, Hobby is a high rank killer very skilled in hand to hand combat and possess goblin gadgets too, i think he can beat down the normal GG and Demo but then he would have to face the UGG.
P.S. I was forgetting, Macendale was at some point cybernetically enhanced, so he's more over Class 12