Desktop wallets.

 They are safe and easy to use, and if the user is not a "complete geek" and does not click on unknown links from spam folders, does not set a password of 12345, in this case, to lose money on this wallet will be extremely difficult.

Web wallets are more insecure because they are often subject to hacker attacks.

Certainly, creators of such services do their best to secure client's funds (for example, two-factor authentication, division of web-purses into "cold" and "hot", entering by IP, encryption, etc.), but such services were repeatedly hacked and money was lost.

It is worth noting that the trend is moving towards improvement, and hacker attacks are more often directed at cryptocurrencies.

The least secure place to store cryptocurrency is in mobile apps, especially if the phone has ROOT rights.

This is due to multiple bugs both in the storage apps themselves and in the mobile operating systems themselves. But then again, apps on smartphones with ROOT rights are most often hacked, so if you don't get ROOT rights on your smartphone, in most cases, there will be no problem with storing crypto, just like with any other banking app.

As in the case of the PC, you should not run obscure applications and links from emails, SMS and other notifications from unknown sources.

Back to multi-currency wallets. To date, the most reliable and popular multi-purses with the possibility of internal exchange are https://askwallet.io/epayments.