what's your budget?
for reference, this is what I have and why:
Intel Core i7-5820K - overclocked to 4.3/4.4GHz, cheapest professional tier cpu, better thermal interface and bigger size means better cooling, cpu socket has screws and not some crappy holes, 6 cores 12 threads for very reasonable price, supports 28 PCI lanes (all cheaper cpus only up to 16 PCI lanes),
Noctua NH-U14S - cpu cooler big enough to cool well even passively, and at loads the huge 14cm fan kicks in while not being excessively loud, by default it spins at around 250rpm on my machine
ASUS X99-S - cheapest X99 chipest 2011-v3 socket mobo with wise PCI layout, decent overclocking power phase design, ability to control speeds of fans by dynamic voltage adjustments directly on motherboard fan headers (so you don't need PWM fans)
4x8GB Kingston HyperX Fury
2666MHz DDR4 - since X99 platform supports quad channel memory, and prices are not so high, there is no reason to go for anything less, plus I can still plug another 32GB to have 64GB in total, which is really neat especially for large projects where lots of RAM gets handy, Kingston ram sticks never disappointed me
RME HDSPe AIO - fairly basic yet professional tier PCIexpress audio interface, aside from stereo balanced XLR I/O it offers also phones output, AES/EBU digital stereo I/O, MIDI, optical ADAT 8in/8out, but what I really love is RME perfect drivers and ASIO Hammerfall DSP, TotalMixFX with its limitless routing capabilities and loopbacks, plus zero latency monitoring of course
EVGA Supernova G2 750W - 80+GOLD efficiency, great performance and reliability, fully modular power supply, plenty of long-enough cables for great management inside the case
Samsung 850 EVO 500GB - SSD is a must for operating system and software these days, it's not just about speed of read/writes, but most importantly seek times and total amount of operations it can do within a second, honestly SSDs are very similar at similar price points, 500GB models are probably best for price/performance ratio
Seagate 7200.14 2TB - I have 2 of them, 2TB capacity is biggest you can format as MBR, which means less problems, 7200rpm offer decent performance, Seagate and WesternDigital products are of similar reliability, so it's just a matter of taste, actually brother has 2TB WD Blue which is practically same, and interestingly one of my Seagates has 2 platters and second has 3 platters although supposedly being exact same models being sold under same product number, performing indeed practically same
EVGA GTX980Ti Classified - overclocked to 1450MHz, since I do also video rendering and other graphics-intensive tasks, I really needed dedicated graphics card, 980Ti is a beast, EVGA is probably best nVidia manufacturer, Classified model is particularly interesting because of serious power phase design, and great cooling performance thanks to well-thought heatsink and two 10cm fans (which don't spin at all unless card temps go above 60°C and so it doesn't generate any noise at all!)
Fractal Design Define R5 - version without side window of course, this case looks stealthy, no teenage-gamer-bullsh!t; well-thought cooling and silence (sound dampening on side panels and sleek custom designed front doors panel) were clearly primary goals when designing the case, as a result case is fairly heavy yet totally sturdy enough, comes with preinstalled 14cm fan in front and 14cm fan in back, I put another 14cm fan in front, dust filters on all fan intakes are included of course
now for the matter of operating system, sadly I definitely cannot recommend Windows 10, can't understand why everyone is so happy with it, so far it appears unfinished, unpolished, tacky at current stage - I am not saying I hate it, I just feel it's far from being ready to replace my Windows 7 Pro as primary operating system - we'll see what the so-praised "Anniversary Upgrade" brings on the table :)