1. Hastings - 1066
2. Stalingrad - 1942/43
3. Leipzig - 1813
4. Cajamarca - 1532
5. Tours - 732
6. Adrianple - 718
7. Vienna - 1529
8. Yorktown - 1781
9. Waterloo - 1815
10. Vienna - 1683
For me, the battles of Tours, Adrianople, Vienna were about survival of races. The arab world would have dominated western and eastern europe. Stalingrad changed the outcome of ww2 and gave the west time to prepare resources to other regions.
I don't think Hastings was that influential. The language didn't begin as a consequence of Hastings in fact it was a successful french invastion. The nobility of england was french and kings such as Richard I didn't even like england. The vikings and saxons continued to live in english society particularly in eastern england and the north and it was in these rural communities away from norman control that english as a language grew. The development of the long bow as a military weapon changed england as a nation not the battle of hastings.
The list is redundant, to say the least. Leipzig (1813, after the Russian campaign) was more decisive than Waterloo (1815) in the defeat of Napoleon. The siege of Constantinople (717-718) was more decisive than the battle of Tours in stopping the Caliphate advance in Europe. Which of the two sieges of Vienna was more important? The one in 1683 was the last offensive effort in Central Europe by a somewhat decadent Ottoman Empire, whereas by 1529 that power was at its peak. In any case, I don't think those sieges or battles were a question of "survival of races". The Balkans suffered the Turkish occupation for centuries, but Greek ans Slavic peoples ans culture survived. In the Middle Ages, I think there were more decisive battles than Hastings as Mantzikert (1071), Ain Jalut (1260) or Agincourt (1415). There aren't battles of the ancient times as Marathon, Gaugamela or Carrhae...
