Agreed, depend on what you want to do with the PC itself will help in deciding the best cost - performance ratio. Custom build is the way to go.
Dont be scared of building a rig from scratch. I had no idea what I was doing, all I did was read a manual and/or watch a video on YouTube. (I can't remember if there was actually a manual) Oh and don't make the mistake I did and forget to buy wifi lolol
I've had my Alienware for 5~ish years now. Not the best buy looking back on it but it was my first pc and quite happy with it to this day.
If it's Desktop PC, then just custom it. With that much money you don't have to worry about lacking funds. Just maximize it!
If your budget limit is 2k to have a good rig then you are safe. Buy the parts and mount it on your own. Take CPU i5k is more than enough for gaming purposes but you can go for an i7 if you want to. For the GPU with your budget man you got freedom lol. Just browse around for the different parts and mount it yourself. I would not advise for a laptop for gaming ], it's not that they are not good but a desktop would be my advice it's just better imo.
The hardest part of liquid cooling is the liquid. Given the mobility of a laptop, shakes are bound to happen. Liquid cooling connectors dont do well when moved, not to mention given the small space inside the laptop, once the liquid spill, say goodbye to your entire laptop. Imo, liquid cooling is a gimmick, you are better off putting a heatsink that extends to an exterior fan. It might be cumbersome, but its more efficient.
Build it from scratch, my advice, intel over AMD for heat control. AMDs have a serious overheating problem. Make sure you measure your case, and motherboard, it's layout. For example my new graphics card, covers two slots. So what I saved on space, I lost in motherboard capability. No linked graphics cards for me. Also do not skip on your PSU, you want it with a comfortable 100w over what you actually need. And go modular! It's worth spending those few extra dollars that means your cable management is top notch. As someone above stated, Benchmark is your greatest asset. Mainly because newer doesn't always mean better. You can save dollars on say your graphics card, that you can spend on having a bigger SSD drive. For example, the Radeon R9 380 is $250, but it's got a benchmark of 5300ish. Where as you can get the RX 480 for $185 dollars, which has a benchmark of 7800ish. The GTX 1060 3gb is the best for under $200.
There are a lot of rig out there if you want to search. Some actually are actually pc vendors with a lot of experience.
Don't buy a 'gaming' laptop. It's just not worth it for the performance it gives you for the price. The processor and gpu can't give the same performance because of thr size consideration. Also some type of GPU would confuse you like GTX960 and GTX960M, the 960m can't hold a candle against 960. It is the marketing way to deceive. Basically just buy yourself a good gtx1080, a decent i7 and fans. You should be good to go.
https://pcpartpicker.com/list/NBvY2R There you go, just something i quickly threw together. Just about 2k USD, You can downgrade the case, PSU and GPU a bit to get it to about 1700 USD. You can also get a 6700k for a bit of savings, since you aren't really getting much with Kaby lake. I also assume that you already have an HDD for storage, if not you can throw a 2TB 7200RPM one in there, they are quite cheap. EDIT: 1. You need to have atleast a 1440p monitor to utilize he 1080 and 7700k, and if you are gaming make sure it's 120hz, makes a big difference. If you don't have a 1440p monitor, (unless you have a triple monitor setup) just get a 1060 and an 7600k And 2. It might be better waiting till March when AMD comes out with Ryzen, All signs point to it being a serious competitor to the 7700k Also, if you have to do get this setup now, OC the CPU to 4.8 atleast, i have a 3570k @ 4.7, been running perfectly since 2012. And you don't need a watercooled CPU to do it, i'm running a TPC 812, works quite well. Jut make sure to clean it thoroughly every 6 months or so.
For the GPU i reccomend either the gtx 1070, gtx 1080, or AMD's 480 if you want a cheaper and higher frames per doller card. i recommend @madmanthan21's setup for this. maybe get some thermal paste and a 2 terabyte hard drive.
O yea, you have to buy thermal paste, it's not expensive though, so it should be fine, i use it every 6 months, when i take apart my build and put it back together, lot's of dust here.
I always see those sick gaming computers for dota in the advertisements... >.> Much too expensive for me though