Personally I added some of my favorites although, like John7755 you can add your favorites as well.
So
Manzikert is one of the interesting one. After Seljuks had won they didn't really enter Anatolia until Romanos IV Diogones was deposed and the new emperor did not acknowledge the treaty. Had th Byzantines won then there would probably no Turks entering Anatolia for the time being.
One of my favorite historical part is about Al Andalus. So that's why
Las Navas de Tolosa hurts me

If lets say the Almohads weren't caught in their camp and really enforced a battle they could wreck havoc in Christian land and at the same time it could have preserved Islamic Andalusia (for a longer time). Sad.
Belgrade, if Mehmed won in Belgrade and secured the Balkans from Hungarians he had his hands free to gobble up the rest of Greece sooner. Maybe finish of Albania as well. And with all that done, go for Rome as well...
Pavia, A French victory resulting in a conquest of Northern Italy? Who wouldn't like that... I don't but sure others will. And Charles V would not have looked for Hungary.
Siege of Leiden, With this one I'm grateful. The Netherlands beign safe from Papist rule from Madrid, God forbid. But Spain would be relieved a lot had they broken the rebellion then. And it would surely affected a lot of events. Maybe even more successful against France and England.
2nd Mohacs, Could have been won by the o so mighty and great and spectacular and... great Ottomans. The results would end in a reconquest of Buda while safeguard Transylvania. If initiative taken, the Habsburgs would go for peace as well. Status Quo.
Slankamen, a battle almost won by the Ottomans until Köprülü Fazil Mustafa Pasha was hit by a bullet. What are the odds? I guess God really didn't want the Ottomans win... regardless, victory was near. And a victory which meant moving the front back to Central Hungary when there was war with France. Additionally saving Transylvania, so to say.
Zenta, Eugene ambushed the Ottomans while crossing the Tisza. Now this battle is more an ambush so there is either avoiding this or knowing that the Imperial Army is on the way and prepare. The Army is experienced and is led by the Sultan so motivation. At this point regaining Hungary is next to impossible. But what avoided peace was about the Hungarian nobles demanded by the Habsburgs but not given by the Ottomans. And ofcourse Mustafa desiring Transylvania back as a vassal. If won, there would definitely a better result than OTL. Austria lacked funds to continue the war as far as regaining Timisoara. A victory would put the Ottomans in a better position to negotiate.
Blenheim, A French victory and occupatio of Vienna could have changed A LOT in Europe. No Austria to meddle in Eastern Europe, one enemy gone in the war of Spanish Succession. France at the point of winning.
Plassey, I don't like British India so I really wished the locals won. Oh well, poor me.
3rd Panipat, Don't know how it will affect the Marathas because although they lost, they still dominated Northern India from 1770 to British Conquest in 1802.