As has been mentioned a couple of times in the topic, neither of the Benders are suitable to replace Xabi Alonso, because neither play the same way as him. However, the players that have been mentioned by others are much more suitable, especially Verratti. I say especially him, because Real Madrid showed some interest in him in real life, for the very purpose of filling the hole that Alonso is going to leave in the team when he retires/if he decides he wants a new experience with a new team before then.
I would go with Lars,personally! Seems to be pretty useful on my career If you want a cheaper alternative, could try Seb Rode for the German league, he's a very good DM and costs maybe half the price of a Bender.