The MPF102 JFET is a popular N-Channel JFET that is commonly used in low power amplifier circuits. The JFET is no longer in production and finding it might be difficult. So they are not recommended for new designs.
The MPSA18 is a General Purpose NPN Transistor which can operate with low noise and high gain. The transistor has a gain value of 500 to 1500 and can operate at a voltage of 45V with 200mA load current.
The KST42 is a SMD package NPN Transistor that has high collector emitter voltage of 300V and a collector current of 500mA. The transistor is a general purpose transistor and can be used for both switching and amplification purpose.
The NTE159M is a general purpose PNP transistor with a maximum gain of 300 and collector current of 600mA. It has a low collector saturation voltage of 1V and can be used in switching and amplifier circuits.