If the fabrics on these Polo's are polyester performance fabrics, which do not breath and will pick, heat sealing is much better than embroidery as embroidery tends to put a lot of stress on the fabric and picks, needle cuts, and runs happen a lot. Embroidery that would not damage the fabric would look like sheet with not a lot of stitches in it. The pellon backing required embroidery on the performance fabrics is hard and cardboard like, not comfortable at all.
Adidas products are usually better than UA products, or at least that is my take and I make products for both companies. Plus Adidas truly cares much more about the end use and user of the product as opposed to UA whom care much more about the UA appearance of a product. UA is overpriced too. Those are my personal opinions based on 26 years of making clothing.
On the polyester fabrics that are so popular today heat sealing is the way to go.