I would say definitely get Copa Mundial for firm ground, and definitely consider Adidas World Cup if you're looking for soft ground.
Once broken in (maybe a couple of games or so) the Mundials are one of the most comfortable shoes I've ever worn, even when walking on concrete. Just a shame that I'm not very good and play in the UK, therefore can only practically wear them for about 3 games a season due to horrendous pitches. The soft ground ones are great, but not as comfortable as the Copas imo.
I've observed three types of player in my team btw:
- Those that buy 'modern' boots and replace them once or twice a season
- Those that buy cheap boots and complain about how uncomfortable they are
- Those that wear 'proper leather' boots :P
Seriously though, they're by far the most comfortable boot I've ever worn and are still going strong after almost three seasons. They also have the advantage of being 'timeless' and by that I mean when they do eventually break you can get a new pair knowing that they'll still make them, they'll still fit and will (probably) still last.
As a heads up, if you do go for these then you'd possibly want the Copas in half a size below what you normally get and the Adidas World Cup ones in your normal size. That's what I found anyways.