Adidas field hockey.....well vented and padded nicely. Go from just above the foot to just below the knee and still fit under your pants (unless you're still wearing the 80's nut huggers). Once used to them you will barely notice they are there.....and nobody else will notice they are there.
Soccer shin guards are better than nothing, but that's about it. If you get hit directly you will still have bruising and pain with them.....but still much less than if you had no protection. These field hockey ones are far superior to the soccer ones.
If you only play 1 league game a night, get the most protection you can....but if you play tourney ball where you play several games in a day, take vetillation into consideration. Also, the ones that go under your socks and under your foot are harder to take off in between games.