(Segwit addresses are the ones that starts with bc1 and legacy addresses are the ones that start with 1)
The purging fee rate for nodes that are using default setting is now around 5.3 sat/vbyte. This means that the minimum fee rate you can use for your transaction, so that it can be broadcasted to the network is now around 5.3 vbyte.
If you are in hurry and you want your transaction to be confirmed very fast, you should use the fee rate of around 10 sat/vbyte.
If you want your transaction to be confirmed in the next few hours, the fee rate of around 7 sat/vbyte should be enough.
(Note that the required fee rate may change over time.)
Let's say you want to make a transaction with the fee rate of 7 sat/vbyte and all your UTXOs are segwit. For every UTXO you add to your transaction, the transaction fee increases by 7*91 vbytes (637 vbytes).
If you have a UTXO worth 600 satoshi, you shouldn't spend that now, since the fee required to spend that would be higher than its value.
If you have a UTXO worth 6000 satoshi, you should spend around 10% of its value to spend it. It's up to you to decide whether you want to spend that now or you want to wait until the network is less congested and you can spend that with lower fees.
For choosing which UTXOs you want to spend, you should go to "Coins" tab on electrum and use "Coin control" feature.
Note: Coin control feature is available only on desktop version of electrum.