I play predominantly forehand, and I will say saw my most improvement from learning to throw a Dart forehand, straight. You really want to focus on getting a clean release, a good amount of spin/snap, and not having any off-axis torque. A Dart is pretty hard to grip well forehand but I'd definitely recommend something understable and on the slower side like a Mako3 or a Leopard so you can work on getting that clean, consistent release. The most common issue I see with inexperienced forehand players is that off-axis torque/wobble, which can absolutely kill your forehand as it'll remove any consistency to your flight, especially if there's any wind involved.