Which version of the Wetbench should I buy?

That will depend on what specific purposes you are wanting a bench for.
    If you’ll be running air cooled or a very basic custom loop, the Basic versions of the WetbenchSX or the original Wetbench would be a solid choice. The Basic WetbenchSX is intended for use with a single 240 or 280mm radiator, while the original is suited for 360mm. Larger sizes like 480mm will extend past the bench, but can still be used.
    If you plan on using an AIO or doing some overclocking, the WetbenchSX Pro tier comes with an adjustable fan mount for directing airflow at your VRM heatsink and additional radiator mounting options. One of these is an AIO mounting bracket, which can sit closer to the board, allowing AIOs without very long tubes to be used.
    The WetbenchSX’s Complete tier offers you the option of every potential configuration and mounting bracket, officially supporting 3 radiators in Flat configuration and 4 in Angled. Customers have reported that the gooseneck fan mounts can also hold up filled 240mm slim radiators, although that is not their original intended purpose.
    Between flat and angled, this is mostly personal preference. For XOC cooling options like LN2 or liquid helium, you’ll definitely want the flat bench. For every day work, the angled bench can require less hunching over while also displaying the hardware more clearly.