The truth is, just about anything will "work". You just have to avoid a very few products that are known to be bad (the exceptions). So it's all about your preferences and how advanced you are with the craft.
Are you ready for a mech? If you don't have a multimeter or any interest in wrapping rebuildable coils, then move on. If you do want a mech, just about anything will work for you, just avoid the KTS. It's tinier than it looks in pictures, and is flimsy, and can short, and the finish wears off on your hands. If you want something cheapish get a K100, or some kind of sigelli mod, or a nemesis clone, or the V3 off FastTech. Fast tech takes about 3 weeks for an order to arrive though, beware.
The other option from a mech, which is more beginner friendly is to get a vv/vw mod. People trash the Vamo, but for the price it is a decent starter mod for a beginner. What I mean by this is you won't be satisfied with it forever, but you will will be satisfied with it for a while. Long enough to decide you really want to go down the Mech road, or you are willing to commit to the VV road with a more expensive mod like a provari.