I'm with stringgreen here. I bet you can't go wrong with either...but they are a bit different. I've really enjoyed my Ayre MXR's...and that was coming off 25 years with tube amps. I haven't heard the latest ARC 5SE+Ref 150...but the reviews/comments are awesome.
Good luck..let us know what you decide to do...
Good luck..let us know what you decide to do...