OK, some general thoughts. If you front-mount, it is preferable to have the tubes at the bottom (see the Gamer's Nexus video linked above), otherwise it will develop a trickling noise over time, and not all AIOs have tubes that are long enough. I have the Kraken X72 (I initially wanted a 280mm, but this one popped up on Carb for a pretty good price), and the tubes would definitely not reach from the bottom of my P600S, and most probably also not in a smaller case. Remember that the airflow considerations are completely different with water cooling, so do think again about intake and exhaust distribution once it is installed.
Looking at the Lian Li you linked, I get the impression you like RGB, so will end up using some kind of control software, and it may be worth it to make sure whatever AIO you get is compatible with whatever software you already use, because they can definitely suck up system resources once there are a few of them.
Finally, I love my AIO. It comes with risks and trade-offs, but in the SA summer it makes a real difference.