I am sure that I am far less experienced than you.. but last summer I did 5 tshirt quilts. I quilted them on my Janome 6600. I just did straight line quilting - cross hatched. I did some FMQ in the borders.
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I was afraid to try to FMQ over the logos.. wasn't sure how they would drag or slow things down while I was trying to move around on them. Here are a couple pictures of one of the quilts. My niece was very happy with hers.
I have seen some that were beautifully quilted on a long arm as well. I just usually try to quilt my own (but not always
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