The McCoys, named after the 20-time champion jump jockey Sir Anthony McCoy, are for owners, trainers, jockeys, stable staff and horses running at Cheltenham and the three other Jockey Club Racecourses in the South West of England - Warwick, Wincanton and Exeter.
McManus took the owner's prize with 20 winners, while Ditcheat-based Nicholls was top trainer thanks to saddling 48 winners - 30 more than his closest pursuer Philip Hobbs.
The jockeys awards went to Noel Fehily (professional), Cobden (conditional) and Page Fuller (amateur), with Adrian Heskin picking up the racing ride of the season for his display on Sir Valentino in the Haldon Gold Cup at Exeter.
The outstanding contribution honour went to former jump jockey McPhail, who has re-trained as Lead Education Officer for Racing To School, a charity that uses the UK's racecourses, trainers' yards and studs to offer young people a unique learning experience.
McPhail said "I have been very fortunate to retrain for a second job that I love. The work we do offers real value to young people and promotes so many positive aspects about racing - as a sport and a potential employer."
The late Many Clouds took the horse performance of the season for his poignant victory over Thistlecrack in the Cotswold Chase at Cheltenham. One For Arthur, winner of Warwick's Classic Chase and the Grand National, was named horse of the season.
The panel comprised broadcaster and Cheltenham committee member Alice Plunkett, regional head of racing Simon Claisse, racing journalist Chris Cook and McCoy.