The only app I have paid for is a Call Control as a blocking app. It has worked great. Uses a large database as well as personal blocking log. I have whole area codes blocked as well as specific numbers. It doesn't ring through, just hangs up. It doesn't give voicemail option all though you can set it to go to voicemail if you choose.
I rarely get spam calls now. It was money well spent. Periodically, I'll go into the blocked call log just to see who has tried to get through. There are usually 3 or 4 a week that were blocked.
My other action is I don't answer if it isn't someone in my contacts list or unless I'm expecting a call from someone. Otherwise, I silence and send to voicemail.