Smartphone - Replacement Time?

My Xiaomi Mi4i is now a Year and a half old, while having serve me fairly reliably, it has as usual with older smartphone, has beginning to hiccup, running out of Memory Space (16G) on a regular basis forcing me to delete photos and apps. Once in a while it at the most inconvenient time reboot itself, the photo app hangs requiring reset and I had already replace the battery a few months back as it need charging every hour.

Mi4i

    

I need to look around for a replacement, an affordable replacement that is and to take advantage of Malaysian Income Tax relief 2017 that allows taxpayers purchasing smartphone to get a relief of the purchase price up to RM2500 (among other items). 

What would I need?  What the minimum Specification I will require, that this new smartphone will last me for quite some time.  Should I switch to another Xiaomi for ease of switching and using back xiaomi apps, or is there better bargains or options out there? 

In Malaysia,  Xiaomi have not release their Redmi Note 4 or Mi 5 yet, so my choice are limited to Redmi Note 3, Mi Max, and Redmi 3s, as I do not want to purchase from Gray importers due to support issues. 

Most important for me is Battery life, I am a heavy user of my Smart Phone, minimum 1.5 hours of Navigation,  All my web surfing, U tubing, Reading, Most of my Photography,  All my E Mails, Personal and Work Related, and of course blogging……….

I will need 2 sim cards, I for my fix (&low cost) number and the other for Low cost Mobile data, definitely better CPU, higher Memory and  Ram then my current Mi4i so 3g/32gb minimum,  Usb to go / Host. 

Metal UniBody, Fingerprint unlock will all be extra, and NFC? May be intreasting to pay with waving the phone around.