Currently, no language even comes close to English in terms of its reach. In fact, English’s reach is so broad and deep it’s hard to think of any competitors. However, I can come up with four (and only four) languages that could be described as currently relatively close to English in terms of global status.
One of the UN languages, Mandarin Chinese, despite being the second most spoken language in the world after English, is not a global language, as some 99% of Mandarin speakers either live in China or are emigrants from China. Chinese has the potential to become a global language in the future due to China’s large scientific and other output. But for that to happen, people will actually want to have to learn Chinese in the same way the majority of the world wants to learn English, or even for the same reasons and to a similar extent Americans want to learn Spanish. For now, Chinese is simply the national language of China, nothing more and nothing less, much like Japanese is simply the national language of Japan. China is a great country, even greater than Japan, but that does not a global language make. Imagine if 99% of English speakers lived in the U.S. or were emigrants from the U.S. and a good portion of the rest lived in Ireland. Would that be a global language? Much the same point about overconcentration goes for Malay and, to some degree, even Hindi-Urdu (which is not a global language because, unlike even Arabic and Chinese, there is zero interest in anyone outside the Indian subcontinent learning it).
Another one of the UN languages, Arabic, clearly does not fit the bill either (though it’s close to it), despite the fact there are many people interested in learning it outside the Arab world. Though it has the economic size necessary for a global language (at least, by PPP), especially if one counts non-standard Arabic speakers, as well as the number of countries necessary (similar to that of French), the language simply lacks intellectually accomplished bearers (in this, it’s little different from Portuguese, which is even less of a global language due to both its high concentration in one country and extremely small core). Saudi Arabia and the Emirates -the closest thing to an intellectual and economic core for the Arab world - are famous for its natural resource exports and religious fundamentalism and nothing else, Egypt, the closest thing to being a demographic core for the Arab world, is famous for its tourist landmarks and nothing else. The Arab world is similar to the Spanish-speaking world without Spain, with lower intellectual accomplishment and living standards on average, and with oil. As a result (and due to the language’s difficulty) Europeans simply do not have the kind of interest in the language Americans have in learning Spanish. Arabic also has a far greater degree of diglossia than Spanish, making it a far less suitable candidate for a global language. The only things Arabic really has going for it are oil and religion, and these do not by themselves substitute for the language’s lack of a core (though religion is at least a powerful one). It cannot reach the commanding heights of global accomplishment in the same way that even Spanish can (due to the existence of Spain).
The present day global languages are the following:
1. Spanish
This is the closest thing to a global language other than English in terms of the number of countries having speakers of the language as the majority. It also has by far the largest number of speakers of the four languages listed here. To a much greater extent than any other language below (or Arabic), Spanish speakers constitute a coherent community with shared and equitably spread culture. As a result, Spanish was voted by my readers as the closest thing to a non-English global language existing today. Though the total intellectual accomplishment of Latin America is not impressive, making it necessarily dependent on the rich West and East, Spain - a rich Western country nearly five times greater in population than Portugal- rescues it from being consigned to an Arabic or Portuguese fate in that regard.
2. French
France has less total speakers than Spanish, but it has a more developed (and more populous) core, and a fairly large (in terms of national leaders using the language, substantially more so than Russian) and fast growing periphery. It is spoken in France, Belgium, a part of Switzerland, Luxembourg, and a dozen or so African countries. There is far more interest in people learning French within Europe than there is in people learning Spanish (the reverse is true in the U.S., but people actually look up to France; Americans tend to look down at the Spanish-speaking countries). I debated placing Russian in the second spot, but, due to the greater development of the French core and the larger size of its periphery, as well as the higher fertility than Russia in both France and the African countries, it only made sense for me to put French second. Though French is in the second spot at present, it would be the most likely language to rise to the top if English disappeared (German simply does not have a periphery even close to the size of French).
3. Russian
The legacy of the Russian Empire makes placing Russian here obvious. It would still have been a global language even in the Soviet era, though, as many millions learned Russian outside the USSR’s borders. The Russian language’s periphery is shrinking, but it’s still there, and it will continue to be there for the next few decades. Russia’s core isn’t highly developed by the standards of French or German, but it’s obviously more highly developed than anywhere in Spanish America and, in terms of intellectual accomplishment, any Arab country. As for the claim that Russia is unimportant, it does have its own Google equivalent, which even Germany does not.
4. German
No, German is not like Mandarin or Japanese. 99% of German-speakers do not live in Germany -it’s closer to three quarters. While Germany’s periphery is not very large, it is in a position near the commanding heights of the world economy to a greater extent than even France. It has the highest per capita actual individual consumption in the E.U. other than Luxembourg, whose residents speak German, as well. It also has the largest population of any country in the E.U. Thus, German is one of the languages most likely to rise to the top if English disappeared. Germany’s intellectual accomplishments are also more notable than those of Spanish, Russian, French, or (obviously) Arabic speakers. As for its periphery, I would not place it here if it did not have one -it includes Austria, most of Switzerland, Luxembourg, a number of people in Brazil, and many Eastern European learners of the language.
Edit: these article seems to confirm my choice of these languages as the top four most global after English (though German as more global than Russian or Spanish), as well as the exclusion of Arabic and Mandarin.
Edit: I have made a map of languages spoken in more than 2 countries of over 100,000 people:
Spanish seems too regional and parochial, concentrated in Latin America, while Spain itself has generally been a relative backwater in Western Europe and on the periphery of the main Western European countries of France, the UK, Germany, and Italy, even during its Golden Age.
French has history and tradition on its side, as the lingua franca and with France being one of the chief countries of Western Europe. And even until relatively recently with US postwar dominance, French was the main second language of Westerners, Europeans, and many throughout the world. The problem now is that outside of France proper, French is mainly a West African language. So like Spanish, it's very regional, parochial, and limited to a backward part of the world.
Russian has geographic coverage across Eurasia, the Soviet legacy, and is more independent of American influence and English than the Western European languages.
German has on its side the reasons you enumerate i.e. economic, political, cultural clout on the Continent. It's the de facto dominant language and culture of Mitteleuropa and Western Europe that's only suppressed by US power and the US siding with the UK and France.
The main argument for Arabic's global status would be religion, as the language of Islam.