But I also started to think twice about using Bitcoin Core because the synchronization process takes a lot of time.
Luckily, you only have to do that once. After that, is "only" downloads 11 GB per month at current rate.
It might be easier to use electrum.
Definitely!
Does using multiple USBs also require having bitcoincore data on each USB?
You only need to backup your wallet, not the blockchain. Worst case, you'll just download it again.
Actually electrum is very simple. One of the reasons why I want to use bitcoincore is because bitcoincore is a wallet created by satoshi.
Do you think both are equally safe? and can you explain a little about the advantages of electrum and bitcoincore?