My gut is to go with the class power upgrade but my old item has so much better sub-stats for me. I’m just not sure how it all scales with damage overall.
For me, the skill selections usually make the difference, as I prioritize those most. Those being equal as in your case here, I look for passives that I’ll actually use. Some of my characters barely ever do melee, for example, so I’d skip a “better” one for one with passives I’ll actually use.
So you think the 4% spellshot increase and 2% secondary class increase might not be strong enough to overcome the superior substats? The substats on the left are mostly useless for me. My ward is frequently low or depleted and I never melee. Movement speed is nice but don’t really need it. Whereas all 3 on the right are pertty good for a deadshot.
I tend to go with sub stats. A few percentage points in class power aren’t enough to overcome the difference 20-50% in a decent stat or two can make, not to mention what happens when they multiply together to go much higher.
Class power also depends very much on the class. Brr-zerker class power, for instance, I find to be very powerful whereas Stabbomancer is less so. It depends on how much the class power boosts the particular thing your build is focused on.
The sub stats are way more important, not even a contest. If you are doing a pixie build you have near perfect sub rolls, even an ascended version of the armor on the left would lose badly.