My thoughts on some of those choices.
MB 3 v J Jones... forget Jones. MB 3 is doing all of the scoring. I actually have both on my roster. I haven't started Jones (who I drafted) ever since I picked up MB at the end of Oct. Check it out- Jones with 3 TDs, Barber 9 rushing and 2 receiving TDs. I'm happy taking all those TDs instead of quality rushing points. The only way Jones is gonna score is if he breaks a long one. Marion is the go-to RB in the end zone/ goal line.
E James? I wouldn't ride your playoff hopes on him either. He's basically become medicore since he got here to AZ, and I think with Fitz healthy again and Matt coming off of a good game, they are gonna throw it a lot more than try to run. With 3 good scoring WR options, he has a lot of weapons to work with that will open up the D more, and I think the rest of the schedule favors a passing attack (I drafted Fitz, and picked up Lineart this week and will ride with both as starters from here on out).
I wouldn't bank on Morris in MIA because I don't think MIAs offense is consistently good enough to produce well even if everyone is healthy. If they fall behind, they aren't gonna get it done with the run.
I'd hang with Deangelo, MB3 and C Dillon.