What's your budget Ian? And what do you want, another slim body cutaway concert acoustic or ?

Your new APX600 (I have one too) is fairly unique in its combination of scale length, nut width and string spacing. For my purposes, in an acoustic that combination of bright acoustic tone, body size, characteristics and features is precisely what I wanted, so I'd buy the same again or similar.

The myriad of choice is bewildering, especially without a specific specs in mind. If I had a hankering to try something similar but different, Yamaha's APX700II or a Cort SFX-1F are two I'd consider at slightly higher similar pricepoints. Great combo of features, tones & playability without spending a fortune.