Indeed, TRON would be suitable for you if your priority is Longevity and low data costs. There are downside to call costs and sms but not for your case.

Pro
- 365 days validity every top-up
- 200MB @ 3G Speed, unlimited data@throttle speed, RM10 monthly
- Daily and weekly internet available.
- whatsapp still good at the throttle speed (forget if it is 32kbps or 64kbps)

Cons
- Troublesome to get the sim pack
- Top up options limited (7-11 is the best they offer apart from online top up)
- Data Subscription Auto renews and have to disable subscription if don't intend to continue.
- No LTE.

TRON is MVNO of Digi network. Check if your area has good 3G reception for digi network.

All prepaids has their good and bad, so choose wisely.