Note: If the call recorder you installed doesn't work, simply just install another one from the list.
Developer: Appliqato
My personal favourite as it's easy to use and deletes call recordings automatically as they fill up unless you choose to save them. It is integrated with DropBox hence can be easily backed up and also allows you to share the recordings to Whatsapp, Messenger or any other social networking site easily with the push of a single button. Good quality voice and free, what more could you ask for!
Developer: Clever Mobile
Gives you the option to enable or disable call recording automatically and also pause the recording whilst on call. Also gives you the ability to protect recordings by locking them but the only disadvantage is the fact that it does not allow you to share the recordings on free version.
Developer: SMSROBOT LTD
Produces high quality recording and also allows you to filter your recordings by choosing which calls to record and which not too. (family, friends etc)
Developer: lovekara
Records all your calls automatically and also organises them so you can view by time, groups etc. Has a simple interface, meaning anyone can use it and is completely free.
Developer: Travel Diary
As the name suggests, it automatically records all your calls without you having to press a button or anything. Also has a nice interface and does the job well.