Which Arduino / shield to use?

Long story short, I am working on a project that requires 4 servos (likely Hitec HS-311) and 2 Nema 17 stepper motors. I’ve worked a lot with servos and arduino, however I have never controlled a stepper from an arduino.

Which Arduino and/or shield combination would best suit controlling 4 servos and 2 stepper motors?

Any help or advice is appreciated.

Any Arduino should be able to deal with that. An Uno is the best for a beginner because most software and add ons work with it.

There are many differences between Nema 17 stepper motors - that just defines the size of the front face (1.7 inches). You need to choose a stepper motor driver that is suitable for your chosen motor. Have a look at Stepper Motor Basics

A shield is not essential but it may make the connections easier. You can get a GRBL stepper motor shield (maybe it requires a Mega) that can take up to 4 Pololu A4988 stepper drivers (if they are suitable for your motors). These shields are often used for 3D printers. I don't know how you can connect servos to the shield. But each servo just needs connection to 1 Arduino I/O pin.