My advice would be a little different although everything Dolby says is spot on..
I think one of the best approaches to this kind of question is for the asker to reword their question so that instead of asking "what should i get?" ask "what is available to me and from that list what would i like"
Wanting a scorpion from arizona would be hard if you lived in australia..likewise many american keepers find certain species hard to get hold of....If you're european the possibilities are greater (except if you're in england) and if you have a connection to germany (as in you can understand enough german to join one of their forums) your possibilities are about as good as they'll get.
So, see what's available to you both physically and judicially and from that list find out what you want.
Dolby's advice about not jumping in the deep end and researching your scorpions is well worth heeding...Not only does their venom have different potency's but their characteristics vary quite a lot as well.
One thing you may want to keep in the back of your mind though is that most scorpions are quite inactive and reclusive. If you want a scorpion to be active during the day so that you can watch it, you might be disappointed. Although saying that i have a couple that are quite active during the day but they are not beginner scorpions.
Your best chance for seeing scorpions active is to get scorpions that can be kept communally (as long as there is food present and the scorpions are adult) so that there's always a chance of seeing something going on.
Babycurus jacksoni would be my first thought if you was american. These are also incredibly easy to breed and the females can have many litters (2 or 3 usually) with just a few months pause between them after just one mating. Also their venom is not considered medically significant...a good nip from a emp might be no worse than a jacksoni sting..and they can be quite aggressive with their prey..
Dolby is right when he says that most people go for emps..This is because they look impressive and they can be brought from almost anywhere...Unfortunately, as most people find out..emps are almost invisible once they've settled into a correctly fitted enclosure/terrarium .. Popularly know as "pet holes" because basically all you'll mostly see is the hole they've dug.
Hadrurus sp are also quite impressive to look at but they do need a good deep substrate because they DO like to dig and they can be both active and passive although....yeh....strange how people experience both extremes with this scorpion..makes me think that it has as much to do with the local environment (where it's enclosure is in the house, vibrations/noise/light/heat) as it has to do with the individual scorpions...So basically, Hadrurus might end up being a 50/50 toss up .. active or passive.
Euscorpius sp are not generally thought about as communal but i once had a colony of E.mingrelicus (about 30) in a 250 liter terrarium and there was always something going on. They weren't what you would consider aggressive scorpions though and they are not very big either. They didn't always use their stinger and when they did it was often kinda half heartedly ... but ... there was nearly always something to see or watch.
So.....good luck with your search mate..