There aren't really any leadoff types on the free agent market. AJ Pollock and Brian Dozier have done it before. But Pollock hasn't really been a good OBP guy since 2014-15, and his injury history makes him pretty scary at 31 years old. Dozier is coming off a terrible season, so I don't think you can count on him being a top of the order guy.
The trade market isn't that much better, but there may be a few options. The Royals should trade Whit Merrifield because he's 29 and probably will be in decline by the the next time the Royals are good, but I don't think they have the stomach to do it.
I could see the Nationals wanting to shake up their lineup, So Adam Eaton could be available. His bat fits well, but his injury problems are of some concern. I know a lot of Cubs fans hate him too...I'm not sure if that's just because he played for the White Sox or if there is something specific he did to make him a bad clubhouse guy.
The Rays are unpredictable, so I guess Tommy Pham could go back on the market...but I doubt it. The Braves would probably trade Ender Inciarte for the right price, but he's coming off a down year (and I don't think it's clear he's much more than a LH Almora anyway).
The Rangers would probably trade Elivs Andrus. He appeared to have finally emerged as that type of hitter in 2016-17, but was bad this year after he broke his wrist in April. If you buy that the injury killed his season, he could be an option.