Question: Defensive backs often get them from interceptions but it's possible for other players have forced fumbles, strips and blocked kicks.

Answer: 
I also believe that this could be very subjective, however, I will try to apply some logic to find a best available answer.

To take a 2014 approach, and looking at the statistics through the first three weeks of the season, it appears defensive backs may have the most influence on turnovers, at least during this season.

To explain, and according to ESPN.com statistics regarding forced fumbles and interceptions, there are 8 players with two or more recorded interceptions this season and 16 players with two or more forced fumbles this season. Of those 24 players that influenced two or more turnovers, 16, or nearly 67%, are defensive backs.
Looking at stats from the 2013...

Richard Sherman had [8 interceptions](http://www.nfl.com/stats/player?seasonId=2013&seasonType=REG&Submit=Go).

The leader in fumbles recovered was [Mychal Kendricks](http://www.teamrankings.com/nfl/player-stat/fumbles-recovered-lost-by-opposition) with 4.

The leader in forced fumbles was [Robert Mathis](http://www.teamrankings.com/nfl/player-stat/defense-forced-fumbles) with 10.

It is tough to track because interceptions are a turnover, where forced fumbles **may not** be a turnover. I cannot find stats on individual turnovers created. There are team turnover differentials, but not stats for an individual (or position).

I would conclude that defensive backs, and more specifically corner backs create the most turnovers based on the stats available. Especially in today's NFL which is a passing league.