only difference is the ram so more apps can run and lte which u dont need u said. i have the i9300 and i think its the best phone for its time so much support modding wise. im pretty sure the i9305 has less mods and support. id suggest the i9300 u wont lag out anyway there are apps that maintenance the task running and kills them according to ur ram and stuff. like android tuner for example. but b4 u buy ether search up there roms/mods to see which u would rather. i prefer stock samsung rom with root. so maybe if u want that the i9305 would be better if theres less roms for that device. but ether phone would make u happy.