The alphacool kits are not really classed as cheap, just not as expensive as it could be. Liquid cool on the other hand would be classed as cheap (still totally fine though) all chinese parts that don't come without the price premium of EU stuff.
Just a heads up there are like 3 versions of the alphacool kits (main difference is the pump used/rad thickness).
I would say it really depends on how you are viewing this possible upgrade. By that i mean, is it more an experiment to see if you like it and are comfortable doing it. Or is it more of a do it right the first time kind of deal.
If its more an experiment then go the cheapest route possible, that way if its not for you, you won't have wasted to much. Then i would pick the Liquid cool kits for this reason, going as cheap as possible knowing it will still do the job but knowing it can be done better at a later date with better gear.
But to be fair that could be said about the alphacool kits also, just they have slight better stuff in them, not by a huge amount if you take their basic kits in comparison. Their slightly more expensive kits have thicker rads better pumps so at that point you can't really compare them to the cheaper chinese kits.
So after saying all that are the cheaper less performance orientated watercooling kits any good. Yes and No, They will have similar performance to a top end AIO/CLC, so its not the performance you would be aiming at but more the fact you wanted to do DIY watercooling. Years ago i got into watercooling, by exactly the same thing, getting a kit and giving it a go, took the hassle out of research and the like. Allowing me to just try it, i have since upgraded/downgraded/sidegraded loops many times over.
So if you go into something like this, do so because you want to rather thinking that they will be better then an AIO. Think of it as tipping your toe into it (pun intended) without spending to much. If you find its to your liking then at that point can you go and get the performance your truly after. Hope this helps and sorry for the mini essay lol.