Nacho Monreal is one of those guys who doesn't grab a lot of headlines, but who is an integral part of the team. You may not notice him a lot, but you'll definitely notice when he's not around. Hopefully, he'll be around a while yet - today in Dubai, as he was showing off the FA Cup, he told sport360 that he wanted to stay at Arsenal longer than the single year he has left on his contract (h/t to Arseblog for running with this).
Nacho has evolved himself into an indispensable part of a vastly improved back line this season, winning the left back job permanently over Kieran Gibbs and helping greatly solidify a defense that needed a fair bit of help after the 2013-14 season. He scores a couple here and there, too, but that's not nearly as important as his defending.
I hope he gets a new deal, and I hope he stays at Arsenal for a good long while.