Hello! Going to buy my 1st smartphone, need advice.

[WuddaWaste]

It's also worth noting that the quad-core MediaTek processors did have some issues endemic to that particular SoC's architecture. GPS being the leading problem. My experience with the 8-Core MTK processor has been rather favorable.

Unfortunately, I have no experience with any of the phones or brands you're mentioning so I'm going to distance myself from this discussion and hope someone more knowledgeable about them can chime in.

But, is a octo-core phone really useful? Or quad-core is really enough for "everything" ?
You don't have to distance yourself from this discussion, I mentionned 3 brands I know, but I'm always hearing another advices with others brands.

It's not about all 8 cores being useful, which is another discussion. It's more about the octo-core's architecture being much more mature and exhibiting less problems than the old MTK quad-core processors. I'm not trying to push you towards MediaTek, but if you do -- I'd recommend the octa-core.

(And yes, my new phone is noticeably hella-faster than my S7589.)

Also, @stevenma61 is a true veteran around these parts. He really, REALLY knows his stuff. Every time I see one of his posts, I pay close attention. To that degree, I've heard good things about Lenovo phones as well.

I owned the LG Nexus 4 and played with the LG G2 and LG Nexus 5 (very similar phones) and very much stand by them as being solid as well. You're on the right path for sure.

Good luck in your decision process!