Check your own calls/sms + data usage monthly. If you use below RM100, then go for iValue1 package (comes with free 1GB data). If you average rm140+, then go for iValue2 RM155 (free 2GB data), etc.
Try to practise own limitation on data usage. I have wifi at office and home. For heavy intense download, like installing apps, youtube, etc, I only use wifi. So far after 2.5 weeks of usage, I only use up ~30MB of my data plan. But through wifi, it must have been several GB already.
In my case, I opt for 24-months contract, as it has 24-months warranty. Also, the device cost is cheaper by rm500 between 12 and 24 months. Billing wise, fully claimable from company due to work purpose
Therefore, in my case, why buy outright, when I can get subsidised from contract ?

yerp..in mind planning to get 32gb with ivalue1 ..btw if buy outright how about the warranty? 1year?2year? and how about purchase from Apple or Machine..the warranty is same or not?1 year? 2year?