Most stores carry several brands of reproduction parts, I´ve had also good experience with CJ Pony.
In terms of aftermarket brands, I´d say Scott Drake parts have very good quality, TMI for interior upholstery
1966 Mustang Hardtop Coupe, Custom Metallic Black Paint, 289 4V C4
1981 Mustang Fastback, Black, 5.0 4V C4
1984 Mustang Hardtop Coupe, Black, 5.0 2V 5Speed (First Car, No longer have it, sorely missed)
2003 Mustang GT, Silver 4.6 Auto
2014 Mustang GT Convertible, Race Red 5.0 Auto
2015 Mustang GT 50 Year AP, Black, 5.0 Auto