I currently have the Apex 2x10sp also and was thinking of doing the same as you. I was looking into new Shimano 105 7000 it would run around $500 or so which includes a new crank.

But then again a used DA or Ultegra 10sp might be worth investigating. Not sure if a new crank is needed if I go with Shimano drive train. Might look weird to keep the Apex crank or it may not even work??? Keeping the 10sp would save a few buck though due to not having to get a new cassette and chain. What to do???