Well, I have to say that, if you are worried that a 'composition' is not yours, because you used a style, first of all, turn on the arranger and let it sit a couple of hours. Did it write a single tune?
Didn't think so.
Maybe it's just terminology, but I tend to assume that 'composition' refers to the melody and chords of a tune, and the lyrics, if not an instrumental. And, other than invoking the 'Riff' feature, you can be assured your arranger will never come up with ANY of those! So, let's forget that one... OK?
Maybe you are thinking of the 'arrangement', which has a LOT more to do with the arranger. But, as you point out, there are a myriad ways to take what the arranger spits out, and carve your own personality onto it. Combine different styles' parts is definitely one way, wholesale replacement of arranger parts with your own playing is another, hiring another player to come in and lay down real parts is another... But, once again, it's you at the helm, making the decisions, NOT the arranger...
Even if you end up using what the arranger spits out with nothing further done to it, YOU are the one that decided this was what suited the composition, and as long as you don't go all 'purist', and insist that everything HAS to always be straight arranger output, you can change, modify, rearrange, replace to your heart's content. It is STILL ALL YOU....
Don't let the machine get TOO much credit, now...
It is still a TOOL, not a 'partner'. It does what you tell it to. You have the final say!
And finally, when you say "Everyone tends to be nice when you play some of your tunes to friends...", well, don't play it to your friends!
Play it to the most critical, knowledgeable person that will give you the time of day...
That alone can save you days of work on a tune that needs work before you even START to sequence and record...