What android version will run smooth in my Galaxy S2?

[Android Central Question]

Hi everyone,

I have a Samsung Galaxy S2 which I am using for 5.5 years. Some months ago, I upgraded my phone to Android 4.1 (Jelly Bean) (Using Kies). Officially, that is the last update for my phone.

The configuration of my phone:
Chipset: Exynos 4210 Dual
CPU: Dual-core 1.2 GHz Cortex-A9
GPU: Mali-400MP4
Internal: 16 GB storage, 1 GB RAM
Battery: Removable Li-Ion 1650 mAh battery
Display: 16M Colors, 4.3 inches Super AMOLED Plus capacitive touchscreen,
480 x 800 pixels, 5:3 ratio (~217 ppi density)

I want to upgrade the OS via custom ROM. Which version of Android will run smooth in my phone ?

Please help! Thanks a lot.

 

[chanchan05]

Try Lollipop, but honestly I don't think you can go much farther. RAM is low for the newer versions of Android.