Who should get the credit for your salvation, you or God? Who makes the decision?
To answer the question we can only ever say that God gets all the credit for salvation. After all it was his plan from the beginning.
Praise be to the God and Father of our Lord Jesus Christ, who has blessed us in the heavenly realms with every spiritual blessing in Christ. For he chose us in him before the creation of the world to be holy and blameless in his sight. In love he predestined us for adoption to sonship through Jesus Christ, in accordance with his pleasure and will— (Ephesians 1:3-5)
There are many views on how faith takes place in sinful man, but at the end of the day it was in accordance to God's good pleasure and will .. Not man's, lest anyone boast!
As to who makes the decision, both Armenian and Calvinists have differing views on this, I will assume we are referring to Justification as both Arminians and Calvinists believe that Sanctification is synergistic. But we have to bear in mind that both views hold that faith is mans response to God's grace.
The distinction then is, how one comes to faith. As both sides take the stance that man can make ''free'' choices. Before even answering that question one must ask what are our choices ''free'' from? Since we are asserting that our choices are free, we must also be asserting that each choice we make is not bound to any force, whether outside of us or by our will's (the natural man - our own conscience). But that is a different topic, related but different.
The view which should be rejected by Christians is Pelagianism (in fact it has been rejected as heresy since its inception). Semi -pelagian has also been rejected as heresy and rightfully so. Both are untenable in light of scripture.
So my answer to the question - Soli Deo Gloria