Hey Ricardo, I've had tons on scorps, some a little more exciting than others.
For a good starter I'd recommend a desert hairy (Hadrurus arizonensis). They're super exciting to watch hunt crickets, especially if you're into seeing them sting (vs. a species like a emperor who rarely stings and just crushes them with their huge pincers). They're a desert species, so sand with a rock or piece of driftwood they can burrow under will do just fine. They dislike humidity, so never spray into the enclosure. Placing them into a new enclosure and watching them make a burrow from scratch in less than 2 minutes always brings a smile to my face!
The toxicity of their venom is similar to that of a bee sting, unless you're allergic in which case you may be in trouble haha. I've been tagged a couple of times by mine and most of them are usually dry stings, so there isn't much swelling. Btw, these guys are pretty aggressive so I don't advise handling them unless you get them really young for practice (maybe 2nd or 3rd instar).
I also have some Babycurus jacksoni which have venom a tadd bit more toxic, but won't kill a human. They're a forest species, with beautiful reddish brown coloring. You need to keep the humidity around 65-75 percent so they can molt properly. They're not as aggressive as a desert hairy, but I really don't handle them too often either (I prefer to watch them =p)
If you're looking for a species you can handle frequently and won't spaz out on you, I'd shoot for an emperor scorpion. I just find them a little boring since they're not too active and the one I had previous rarely stung any crickets. I'm all about the action =)