The Dutchman struck six times in five matches in April, while the Spaniard guided his side to three wins and a draw last month
Van Persie netted six times in five league matches, including a stunning hat-trick at home to Aston Villa which clinched a record 20th title for Manchester United.
The prolific Dutchman also scored on his return to the Emirates Stadium against former club Arsenal, and leads the Premier League scoring charts with 25 goals.
He unlikely to be caught either, as his nearest rival Luis Suarez (23) will not play again this season, having been given a 10-match ban for biting Branislav Ivanovic.
Van Persie, however, was pipped to both the PFA and FWA Player of the Year awards by Tottenham star Gareth Bale.
Benitez guided Chelsea to three wins and a draw in April as the Blues close in on a third-place finish.
The Spaniard will also lead his side out against Benfica in the Europa League final after seeing off Basel in the semi-finals of the competition this week.