Yet Another Ring Question

I know how much you all hate these, but this is here solely for the math lovers to go crazy (easy math, another reason why it's Q&A).

ArchMages. 5% Critical Rate for 50% (?) Critical Damage after the Big Bang patch (from passive Beginner skill).
With Self SE (again ?, but iirc 10% rate for 15% damage).

= (?) 15% rate for 65% damage.

Now here's the question:

Critical Ring? Or Magical Ring?

Assuming they'll remove the critical damage from the Magical Ring like they did the others, the question essentially comes down to which is better stacked with the above: a ring with 10% Critical Rate and +1 MATK, or a ring with 5% Critical Rate and +5 MATK?

I'm curious to see both results, one assuming the crit system is multiplicative, and the other additive. All of my calculations thus far (which are most likely horribly incorrect) point towards the Magical Ring, since it appears that +4 MATK boost edges out the critical rate boost for acting as an overall raw damage buff, but I'm wondering what EXACTLY is the case.

Thanks guys!

My guess is critical would still win out. Even though 4 more magic attack would equate to higher raw damage, an increased critical rate would still prove better, with 65% more damage every 4 attacks or so.