If it's the title Parker wants then I'd say Jennings after he fights Rivas, and get closer to a shot at Wilder. If not the title, then Browne in NZ, Chisora/whyte winner, then Junior Fa in 2 yrs if Fa fails at a title charge.
Yeah if I had my preference it would be Browne next and then someone of Jennings' level after that. I wouldn't be suprised however if he had one more tune up before taking on the likes of those 2.