It depends on where you (i.e. your devices) are coming from. I'll assume USA.

Type F is the most common type of socket you'll find here. It's compatible with type C and E plugs as well.

AC voltage is 230 V at 50 Hz. Almost all portable electronic devices these days are universal (i.e. 100-240 V, 50/60 Hz) but check the label on the power adapter for your device just in case.

SKROSS adapters are the most popular around here and are probably the first ones you would encounter at the airport. They are pricey, versatile and high quality. But any cheap adapter from Amazon will work. Things to consider:

• Size: The most important factor, since you will be dragging it around the world.
• Versatility: If you tend to visit multiple countries with different plug types during a single trip, consider an adapter that supports all the types you need. These tend to be bulkier and more expensive so otherwise prefer the simplest, smallest and cheapest ones.
• Safety/Insulation: If you need to use high-powered, especially heating devices that lack double insulation, consider buying an adapter with ground connectors. It has the third hole for the Type B US plug and has the metal side connectors of the Type F EU plug. This will protect you from electrocution if your device malfunctions.
• Quality: I've had some cheap adapters that have trouble staying in the wall and keep falling out. Read the reviews and see if there are complaints.

Something like this should be fine for any device supporting the local voltage (looks small, safe and durable).

In contrast the cheap-o ones look like this but they are not grounded and often have trouble staying in the wall if you tend to yank the cord of your charger.

If you REALLY need to convert voltage as well, there are step-down converters on Amazon for like $30-50 but they are heavy and a pain to drag along.