Call me crazy, but I actually think that D3 is a very nice looking game. I also enjoy PoE's art style and graphics - but D3 is nice. It doesn't need to be pushing graphical-boundries - it has a nice artstyle, it's consistent and it's easy on the eyes.
The main thing that is hooking me into D3 right now though is - game play/combat is fast and fun as hell. Been switching between a Demon Hunter and a Monk, and dammnit - the Monk is probably the most fun I've had playing a melee character ever.
The various main-attack skills are fun to play with, and depending on if I'm solo or in a group I'll switch betwen whatever one makes most sense (the one that acts like flicker strike is fun). Tempest Strike as a secondary attack puts a smile on my fast - that skill is fun as hell to bust out.
A self-heal that also damages undead, AoE blinds, skills that pull enemies into me - and also ones that push them away. Just got a passive that heals me for any amount of spirit that I spend - even at lvl 16 the various combos and interplay between skills is fun to mess around with.
During combat I need to constantly switch between diffrent attacks. It's not just '1-2-3 spam' attacking. I use my primary attack to fill up my spirit, if the enemies are spread far away - I might use my AoE that sucks them in so my short-range AoE melee can hit them. If they are spread out I might use tempest rush to run around and hit them.
PoE? more often than not - I use one attack, things die in 1-2 hits. While playing a ranger is a little more fun - I find melee in PoE to be kind of bland. Things did spruce up a bit with the addition of Totems, and in harder situations I might use a totem, shield slam - but 90% of my tactic is just spamming ground-slam.
It is kind of fun to setup a shockwave totem, position myself with ground slam and watch enemies not be able to reach me - then use shield slam to run around and pick off stragglers. Just that more often than not - doing this is less effective than just spamming 1 skill - and I'll do the above more for the fun of it than the effectiveness of it.
God, things get boring when it comes down to 1 vs 1 with a yellow that has additional health + health regen, my finger gets tired from holding down my attack key while waiting for it to die. It's not hard, its dull as hell.
With my ranger? Casually walk around and fire a poision arrow or two. If it's a fast group of enemies - Temporal Chains, if it's something with health regen - Vulnerability.
So much of the combat in PoE relies on 1-skill spamming and having things die in 1-2 hits, it leaves very little room for dynamics/tactics in combat.
This isn't to say PoE is boring - I am rather enjoying it also, but the combat is lacking a fluidity and melee combat needs quite a bit of work to a) be balanced, b) be fun and engaging.
One thing that PoE does have going for it though is that 'crack factor'. A large part of that comes from 'everything always being slightly out of reach'.
Get an item? Great - but even if the stats are good, it might not have the number of sockets you wan't/need. It has the number of sockets? They might not be the colours that you want. Has the sockets and colours? It won't have the links you want.
The constant carrot-on-a-stick and endless fiddling that you can do with your gear setup is pretty fun, and once you get things right it is immensely satisfying.
The world is dark/gritty/interesting (although map generation needs a lot of work), the passive-grid is neat to play with, and I do really like the gear/socket/support system for skills. There is a certian heaviyness/weight to the world in PoE that pulls you in - and wanting to get that next level, next skill point, next item / skill / currency item.
The permanence of your choices really gets you attached to your character and invested in his progression. I feel a certain attachment to my characters and having it be something I obsess over every small detail of is rewarding in it's own way.
In Diablo 3 - it feels like everything is there just as you want it. I'm not really feeling that sense of excitment over items yet - something drops, it's a a fairly straight forward of 'Is it better than what I have right now? ok - swap it'. Item finding is far less exciting so far (maybe it'll change in later acts/difficulties).
I remember finally getting a damn 3-linked red socket item after the patch so I could finally put +hp gain on hit/+item quantity find onto my primary attack - made me damn near giddy - then finally using the orbs/etc on it to make it a very nice rare item.
For a genre that has traditionally been so much about the joy and thrill of finding loot - D3 hasn't captured the crack-factor of that yet just for me.
TO me, it sort of comes down to - Diablo 3 is proving to be more fun, Path of Exile is more satisfying. Both hit the 'this game pleases me....' in very different ways - and one isn't nesscairly better than the other (to me), it's more 'What am I in the mood for today?'