Based on your preferences and budget of 15k, I would recommend considering the Xiaomi Redmi Note 9 Pro. It offers a great balance between performance, battery life, and storage capacity.
The Redmi Note 9 Pro is equipped with a massive 5020mAh battery, which should easily last you a full day of heavy usage. It also features a Qualcomm Snapdragon 720G processor, which is powerful enough to handle gaming and multitasking without any issues.
In terms of storage, it comes with options of 64GB or 128GB, and you can choose the latter to meet your requirement of having at least 128GB of storage.
The display on the Redmi Note 9 Pro is a large 6.67-inch IPS LCD panel, providing a good gaming and multimedia experience. It also has a quad-camera setup with a 64MP main sensor, allowing you to take impressive photos.
As for software, it runs on MIUI 11 based on Android 10, which provides a smooth and user-friendly experience.
In terms of the latest technology, the Redmi Note 9 Pro was released in April 2020, so it's a relatively new device that won't feel outdated anytime soon.
Overall, the Xiaomi Redmi Note 9 Pro would be a solid choice that meets your requirements for long battery life, ample storage, good gaming performance, and a relatively new release.
PH