I will say third one is best try to promote pics0 . If you can work hard on it than you can get good return in future .
Well it will continue having the same purchase value unless you work on to develop the domain with websites.
try with something that have any mean, but anyway like others say - the content and idea is the most important.
My philosophy to registering any domain is always after keyword research, you want something that is going to help you target your main keywords, unless you have money to spend and a great idea to promote with these obscure domains, not being funny, but if you were to offer me any of these domains for free, I would not take, as there not worth the renewal fee I would have to pay.
i prefer LLLL.com rather than LNLN.com it's easier to remember. so your domains are not my favourite.