MTK also have a fair share of problem also...
very hard to tell bro... i do change 1~2 device per year...
until now hard to tell which processor is better... exynos for Samsung u see on the spec or benchmark is very good but again there will be some ppl complaint also...
there isnt many ppl complaint about the over all package should be iPhone, until now the system has been smooth or acceptable speed on their 3~5 years old device...
which android has problem to catch after 2 yrs... there is some exception like Nexus device or some ppl plashed AOSP roms...
so far hard to tell which is the best combination...
FYI I found that MTK chipset also quite hot after sometimes of usage... i'm using HTC 820s which is using it... used b4 Lenovo L780 and P70 also same, but slightly better...
and also MTK chipset doesnt have very good system update (Android) records on their devices..
I'm also using a 820s now, which not generating as much heat as SD and performance average and battery fantastic (with heavy whatsapp n emails). This 2 points made me love MTK, hahaha...