Shurelya's is just wonderful for both initiating with your ult and pulling someone as far as your ult will allow. Make yourself learn to use active items; if you don't, you're missing out on some of the most powerful items in the game. It also provides CDR.
Don't; upgrading your sunfire costs 800 gold and provides 20 HP and the aura. It's a horribly cost inefficient item. Randuin's is a much stronger choice.