Not that i have tested Lukaku, but i do have Mitrovic, and he is one fine piece of as... I MEAN PLAYER! Erm, but in all honesty, he scores for fun, he is also better techically than Lukaku and is in my eyes, the complete striker, cause he is a boss in the air, he can pass, dribble, shoot, he is the whole package.
I also got Shaw, i am not sure if he got a higher pa than Alaba, but he is an absolute boss in defence, both offensively and defensively.
Both of these are definite purchases in my humble and so very honest opinion
I personally like Alex Telles at LB... didn't know about him untill he broke into the Brazil team for 2014 world cup & put in 7.88 performances, also winning young player of the year. Got him for around ?7.5M in the second season. For strikers I'd say Lukaku, Mitrovic & a developed Gabriel Barbosa.
In my first season with Man Utd I bought Luke Shaw for ?25M and Gabriel Barbosa for ?3M. I think Luke Shaw was worth it, he gets great attacking attributes for a Complete Full Back so he is amazing for attacking. And his dribbling just becomes insane, to the point where he'll get the ball and just run past everyone down the line.
On my PSV save Willems at LB has been insane and rapidly is developing into the best LB in the world just 2 seasons in. Mitrovic has also been another level, he literally has it all (finishing/pace/heading/strength) and I have Barbosa bedding in as a IF L.