Electrum is good as a main wallet on a laptop/desktop for big transactions. It is more secure because you can set up a multi-signature wallet which works like two-fator authentication (you get a code on your phone + password ). Also, on Electrum you get to choose the transaction fee/speed as you like. If I am not in a hurry, I choose the lowest transaction fee even if it will take hours to complete. This is why its good for big transactions as the fee becomes significant for big amounts.