Features and price will determine which Tablet to get, here are a couple of comparisons:
Asus Eee Pad Transformer Vs. Samsung Galaxy Tab 10.1 Samsung Galaxy Tab 10.1 vs Asus Eee Pad Transformer TF101 | News | TechRadar UK
But here is the kicker:
Samsung 16GB Galaxy Tab 10.1 with Wi-Fi : Android Tablets - Best Buy Canada ASUS Eee Pad Transformer 10.1" 32GB Tablet (TF101-B1) : Android Tablets - Best Buy Canada
Also, Samsung has no extra memory capability while the Asus can take a micro SD card.
There should be 3G versions of the Asus sometime soon, or so it is reported. For some, that is not a big deal though. I would recommend doing a lot of reading, there are many choices out there, and in the end you have to be happy with your own purchase.