[Q] Changing in-call/phone app topic

I've been using a Galaxy S3 for the last 3 years. I was happy with it but decided to upgrade to the One plus One.

I really don't like the default kitkat phone app. I don't like the contacts or the in-call screen. The buttons on the in-call app are too small. I really like the Galaxy s3 phone app and contacts app.

Is there anything that I can do to change the default apps? I installed GO SMS, and I really like it. I like the contacts part of that app too. I've tried RocketDial but I don't like the dialer app and the in-call screen is the default kitkat screen.

Could someone please help me with this??