Think we need to decide how we want to play first and foremost. If we want to keep up with this brand of football then by all means, get the best defensive mid in the league. I said a few months back I wouldn't take Kante but he's a tier above Coquelin, and the distance will only increase as he gets more games under his belt. He'd be a good buy.
Personally I think we should build a different, more durable midfield altogether, but doing so would mean we'd have to put down serious money. Gündogan and Kroos might be on the market this summer. Just imagine those two behind Özil.