Private sale: e.g. eBay classified/autotrader/newsagent window/local paper/notice in window
Pro: you get more money
Cons : people bothering you to view and timewasting, making silly offers, paying with bouncing cheques/forged money/ scams etc.
eBay rake off a large fee.
Take to dealer/webuyanycar.com
Pro: once they have the car, you can forget about it, they pay the money and not come back.
Con: very much lower price. webuyanycar.com have a reputation for offering you a good price, then when you take it round to their agents, they find loads of "problems" and offer you a much lower one, which most people accept, as they have had time off work and arranged transport to make the deal.
Pro: you get the money quicker.
Cons: low price, auction fees.
Pro: it might sell.
Cons: low sale price, loads of timewasters, eBay fees.