Some people say to take as many saurus units as you can cause they have good stats, some other people say that people should take at least 1 skrok unit. Whats the use of each of these units/which one is more useful overall?
This one has been debated about as much as I've ever seen a topic. Saurus are solid and dependable; it's hard to go wrong with them. Skrox take a bit more finesse to use and not have them turn into a liability, but they do offer some advantages: Movement speed, cheap extra ranks, armor-cracking S6 hits, aquatic, a little shooting, etc. I use Saurus to hold my battle line together, and send the Skrox out to flank and blitz key targets. They work great against things with few but powerful attacks, like Bloodletters. Things like frenzied Chaos warriors with double hand weapons will deal out too many attacks, and you won't keep your ranks long enough. Look around on the forum here, and you'll find a dozen or so discussions on the subject. Should be plenty to help you on the right path.