A padded mat is nice if your actually Shooting in the field with uneven ground, rocks etc. For comforts sake.
And very light and thin mats is likely to flap or fly off if you shoot in windy conditions.
If you live in a enviornment that has much rain like me, and you actually shoot in such conditions waterproofing is a must too.
As for size anything that does not cover most of your body is a waste if your ever shooting outside in wet terrain fx, knees down at least.
So id say the best mat is determined by your use and surroundings.
Some of them also has some useful features like edge or laces to help support a bipod.
Some tucks compact and are lightweight.
Attachments for tent poles is a useful feature where i shoot as a 10-15 ms wind can make them fly off.
There are a lot of decent choices, you should decide what features you want first and make a choice from there.
Triad tactical, TAB gear, Voodoo, Crosstac, Midway, Creedmore sports, CED, Champion shooters supply etc.
All make good quality mats, although not all of them are 'tacticool', but it really does not matter anyway, a good mat is more important then it's looks every time.