Upgrading me PC specs (Graphics card and SSD)

For the GTX 1060, the MSI Gaming X is outright better than the Gigabyte G1 Gaming in temperature and minor advantage in term of performance; both MSI and Gigabyte have multiple versions of the GTX1060 so this comment is specifics to the comparison of these 2 top-of-the-line models from either manufacturers only (well, Gigabyte true top-of-the-line is the Xtreme Gaming series, but I don't think they've announced a GTX1060 Xtreme). Your K281 has room for graphic card of up to 315mm in length; both the above mentioned GTX1060s are around 277mm so they'll fit inside the case with some room to spare.

The GTX660 is specified as a 140W card; the GTX 1060 is specified as a 120W card. You're not going to suddenly see a lot more heat than what your current card is putting out. That being said, you may want to get some utilities like MSI Afterburner (it'll work with cards from other manufacturers) and run it to see how hot your current card is getting while idling (nothing else but Windows running) and during heavy load in gaming.

In most case, liquid cooling for GPU only matter if you already have a custom-loop liquid cooling system (i.e not one of those closed-loop all-in-one like say... the CoolerMaster MasterLiquid Pro 240 that was reviewed recently right here on toms) otherwise, it's a waste of time. And to end that line of thought, your K281 does not support water cooling.

In regards to SSD, the Samsung 850 Evo is often recommended for its top-of-the-line performance and 5 years warranty. Your local retailers may not honor the warranty part (if they can get away with it, a local retailer may offer you 3 years only) which could very well affect whether you actually want to go with a Samsung SSD or not.

Out of my personal experience, 1x Samsung not use as OS drive died after a period of being on life-support so I was able to get some data out of it (albeit with some corruption); 2xSamsung drive as OS drive and they both died without any warning whatsoever, one of them died while running scan disc on the failing Samsung mentioned above; 1x Samsung still working with no sign of issue but given my prior experience I'm not going to say that its safety is a sure bet.
So, just from my own personal experience... I do not trust a Samsung drive to be my OS drive, although there are a lot of people whose experience with Samsung are much more positive than mine so I'm not going to tell you to avoid using a Samsung drive at all cost.

With regards to the other SSD manufacturers:
Sandisk is the main competitor with Samsung in regards to speed and from people's experience, their SSDs have solid reliability records. (given my personal past experience, I'd prefer Sandisk over Samsung if prices are similar)
Plextor drives while not as speedy as either Sandisk or Samsung, are considered as very reliable (meaning good value if cost similar or less than Samsung or Sandisk).
After those 2, there are Intel (up to the 535 only, the 540 isn't of good value unless it's significantly cheaper than the other SSDs because it's an outlier for Intel SSD), Transcend (SSD370/370S, low cost for solid mid-range performance and I've had good experience with Transcend flash product), Adata (the SP550 is a top value recommendation for performance/price, meaning if it's available for significantly less than the Sandisk/Samsung then it's a good buy).
Crucial/Micron are a mixed bag of good and dud, and OCZ are mostly dud.

These are just very general thoughts because I have no idea what SSD is available at what price where you are; for example where I am, a Transcend 370S 512GB is $50 less than the equivalent Samsung 850 EVO whereas in N.A they're about the same.