I play exclusively OCCs now. I recently won one on Deity by space race - although I was helped by a SGL, and an 80% archipelago map. 20k culture at deity is fairly easy, as is diplo, and neither should really be considered "wins," since all they really require is sticking around until the end of the game. Nabbing at least 3 ancient wonders is easy, even on Deity, and you can often get 4. You'll also be building at least Cop's Observatory, Newton's U, Theory of Evolution, and SETI along the way, giving a fairly easy path to a 20k culture win, provided you don't get attacked. Also, you'll be trading so frequently with everyone that a diplo win is all but guaranteed if you get the UN, and doing so is easy to accomplish. Space requires a lot of wheeling, dealing, and espionage in the modern age, and isn't guaranteed like Diplo and 20k are,
Scientific is the must have trait. You need those free techs at the industrial and modern ages to make some coin and keep up in tech. Nothing is more crucial to a OCC win than those techs. Starting with Bronze Working is a nice bonus too, because you can't count on being able to trade for or find any of the early techs and it ensures you can build the Colossus right away.
Worthless traits in a OCC are Religious, Militaristic, Industrious, and Commercial. War should be avoided at all costs, changing governments happens maybe twice, commercial is only good with a lot of cities, and faster workers are irrelevant because a second worker can very easily be built early on. Agricultural is OK, but you're going to want to choose a start with some bonus food anyway, so this isn't all that important.
Seafaring is surprisingly good, actually, but as much for starting with Alphabet as anything. I've built my entire OCC strategy around having Alphabet at the start, and it works like a charm. Begin researching Writing at 10%, then research Philosophy as high as possible (you'll be using the luxury slider). On Deity you can get philosophy first almost every time, and then you get Literature for free. Build the Mausoleum and then the Great Library, and you're set. The only downside is that you get an early GA with the Byzantines, but that's not fatal. You can also build Curraghs right away, and make contact quickly. Seafaring helps establish contact. You also start coastal, getting rid of the need to waste turns wandering to the coast.