Choose one wallet and stick to it except if a change that you don't like appears.
Bitcoin core- For developers and people who care about security as bitcoin core verifies the entire block. It does take more space though.
SPV clients (MultiBit/Electrum)- For normal users, SPV client is usually enough and is ideal for people with smallish storage space. The security is not to the standards of Bitcoin core though.
I hope Electrum will push their security to new levels, i plan to store tons of bitcoins will them in the future.
I hate to keep blockchain on my pc, its just a waste of space for my small pc.