i allways thought brek shea was a better LM, i've never had him myself but i've seen SS's showing him about 5-6 seasons in and hes pretty good, not sure if hes man u class though
Matlock is defo one of the best LBs in the game at his prime...you could also try Nyatanga from Derby, he always turns into a world beater in my saves. You could probably get him really cheap too.