Most people I know use "Send money to friends and family" option when sending money with PayPal, because it has less fees and the sender pays it.
However, as of April 19th 2018, PayPal USA changed this fees policy.
They now charge a flat rate of $2.99 for transfers to Europe, Canada, Australia and some other countries (please check it yourself), while all other countries are $4.99 per transfer.
This is more than the fee charged when using the Goods/Services option if you are sending less than $100, as this fee (which is paid by the seller) is about 5%.
Therefore, if you live in USA and want to send money (under $100) to a country other than the above list, you should use the Goods/Services option instead, adding an additional fee on top.