I have an Enthoo Pro (Luxe shares the same frame as the pro), its a wonderful case. Very modder friendly (almost everything is screws not rivets so things like the ODD bays can be removed for a possible 360 in the front with a little modding), very good cable management, great value adds (PSU cover, plastic divider box for screws, 6 fan PWM controlled hub). As far as radiator support goes, the Define and the Enthoo have the same options (the Luxe meets the same same thickness options as the Define R5) but the Enthoo Pro has built in support for reservoirs and pumps (the Luxe comes with the pump bracket but the Pro has to be bought separately) as well. Personally I think the Pro is the better case because it has a bit more going for it. Now don't get me wrong the Define R5 is a great case but if you are looking for a no compromises wc case I'd say get a Luxe.
Also the Enthoo Pro/Luxe has better cable manageability IMO
The max front on the phanteks is 280, sorta, if you remove the optical drive bay you can finagle a 360 in the front the only issue is that you won't have any mounting holes for the third 120 but it can be done. A front 420 should be possible as well
Also the Enthoo pro is barely a full tower (probably the smallest full tower on the market)
I don't feel like anything is better for the money than the enthoo line of products. Their design is amazing, clean and aggresive without screaming "GAMER!". Hardware Canucks feels very strongly about recommending the enthoo cases as some of the best they have ever reviewed. The Define R5 though actually looks pretty amazing and I dont even like cases that look that plain. If its anything like its predecessor its a sure winner.
Just to clarify about the water cooling capabilities of both these cases.
Excluding modding and radiator sizes that are not officially supported, the Enthoo Pro can have a 3x140 45mm thick rad in the top with fans in push or pull before reaching the motherboard.
In the front you can have a 2x120 thick 60+ mm rad.
While the Define R5 can accommodate a 420 in the top also, it can only be 30mm thick with push or pull fans. In the front you can have up to 360 but not while a 420mm is in the top.