Adapter

We need a bit more info to give a full answer.
Q1) What type of plugs are on these items? I.e. which country do you come from? Are they North American plugs, Australian plugs, Elbonian plugs or what?

iPhone chargers are usually capable of using both types of electricity (110-240V 50/60Hz AC) (but please double-check) and have 2-pin plugs.
In which case all you need is a 2-pin adapter to convert from your (whatever-it-is) plug to a 2-pin "Europlug", which works in both Italy and Switzerland.

The anonymous "appliance" could be a problem.
Q2) Does it have a 2-pin or a 3-pin plug? (and which country's type of plug)? This decides whether you need a 2-pin or a 3-pin adapter.
AND, 3-pin plugs are different in Italy and Switzerland, so you would need two adapters.

What type of electricity will it work on? Europe uses 230V 50 Hz. Does you "appliance" work on thta?
If not, you need a voltage conveter as well. This is big and heavy and expensive. Probably best not to bring this appliance.
If you plug it in and it doesn't accept 230V, it will burn out, be damaged and trip fuses in the hotel.
You need to read the small print on the appliance's label.

What kind of appliance?
- 110-240V Phone chargers, recent non-grounded computer chargers, camera chargers... work with any Continental European adapter (two round pins)
- 110-240V grounded appliances (like some big computers) require specific adapters that are hard to find in stores. Try your luck online or look for one locally, they are different for Switzerland and for Italy too. But it's unlikely you need this
- 110V appliances won't work. You need either a converter (not recommended, heavy and unreliable), a dual-voltage appliance, or a local appliance.

I should also add that the non-grounding, two-round-pin "Europlug" adapter, which fits in a European receptacles, is limited to devices that draw no more than 2½ amp (575W at 230V), so hair dryers are out. They are also not safe for US appliances with polarized plugs (one blade wider). Leave such appliances at home.

At one time I had a laptop with a US grounding plug, and I could use it with a Europlug adapter in Germany's Schuko receptacles because the receptacle had a round recess, and the grounding pin fit alongside the Europlug adapter inside the recess. I don't recommend this because it defeats the ground, and I quickly replaced the adapter with a grounding one. But this "trick" would not work on a recessed Swiss or Italian receptacle.

First, an adapter is just a piece of plastic with a couple of metal prongs. They are all the same except for a little difference in shape. So -- no best adapter. What appliances ?? That is the scary part of this question. An iphone is fine with just a standard wall plug adapter that you can buy just about anywhere.