A properly set-up WorldGuard is amazing, but it's really not an issue of the 'best plugin,' more of you finding what works for you and your players.
kiligir How would WorldGuard protect from players cheating with mods like X-Ray or a fly mod? Or in any way besides greifing for that matter? I'm just wondering because I use WorldGuard on my server, but I only really use the region protection properties.
Perhaps I misunderstood your question. NoCheatPlus is an amazing plugin that does about everything you'd want it to.
Well currently there is only NoCheatPlus, NoCheatClassic and AntiCheat that should work. I would try all and make your opinion which one fits your needs.
If you want to scare hackers and griefers away from your server. The combination of AntiCheat, WorldGuard, and NoCheatPlus will usually make them leave right away. But make sure that you give them permission to use /plugin so they can see that you have them .
Never run AntiCheat together with NC+. That will just end in tears... just use one of them. You wont really get more protection if you use both together.. you just get a performance drop and some more errors.
MyPictures, Interesting. I've always used AntiCheat as my main hack protection. But then I configure NoCheatPlus accordingly because I feel it is more configurable.
Your server = You decide what plugins go on it I just don't recommend to run AntiCheat and NoCheatPlus at the same time. It wont give any extra protection or anything like that so only use one of them.
To be honest nothing (maybe?). Its more made to prevent griefing and such but it doesn't scan players for illegal behaviour.