I still can't see him transferring because Tua is prone to ankle injury and Jalen comes in does great things doesn't his stock go even higher? RTR!
I think Jalen would be drafted if he entered the NFL draft this year. He has enough playing time that someone will take him, especially after recognizing his improvement at the Combine or Pro Day.
So the question isn't "where does Jalen transfer." That's the wrong question.
The question is -- would it be worth it to Jalen to spend another year in college at another team learning another system and competing against existing players for the chance to start and improve his draft stock? I'm not sure that it would.
While this worked for Russell Wilson, who went from NC State to Wisconsin to get noticed, Jalen already has played at the most visible school in the country. He already led his team for two seasons to the Championship Game. (He would have beaten Clemson if the defense could have held.)
I don't think Jalen needs more playing time. He just needs to improve his game, which clearly he has done this year while backing up Tua.
The only question I see is, does Jalen stay another year at Alabama?