Which gtx 970 should i choose?

i suggest you to buy-> EVGA GTX 970.

If price isn't a problem I am currently a big fan of the MSI gaming and Gigabyte G1 gaming versions. Both have very good coolers.

To choose between them is just personal preference both are great cards and will perform within 1fps of each other.

This teardown article makes it quite clear exactly just what the physical differences are between the cards.

http://www.bit-tech.net/hardware/graphics/2014/09/19/nvidia-geforce-gtx-970-review/1

If you look at the "nitty gritty" with regard to power phases, connectors, fan control, memory cooling, chokes, capacitors, fan size, heat pipe sizes, you can see that these physical and design differences will explain for example why in every published review I have seen, .... of the three cards in the teardown review, only the MSI Gaming is able to top 1500 MHz boost clock. The ranking put forth by the articles author is MSI > Asus > EVGA which is historically consistent through the 7xx and 9xx series..... before that (5xx and 6xx series) Asis and MSI switch places

Unfortunately, Gigabyte didn't submit a card for the roundup and looking at other reviews, while comparisons are sometimes difficult due to different test hardware, the Gigabyte G1 and MSI share overclocking wins with Gigabyte winning more than it loses. On fan control and noise, gotta give it to MSI who not only turns the fans off at lower temps (feature was introduced in 2008 and and Asus adopted it this year) but also controls the two fans independently.

I have been using the MSI Gaming or Gigabyte G1 in our builds (mostly MSI cards with MSI MoBos and Gigabyte w/ Gigabyte MoBos) . The Gigabyte gets the higher overclocks more often that not by < 1 fps .... but the G1 doesn't have the fan feature and the G1's length of 12.28 inches puts it at 1.7 inches longer than the MSI and the extra length oft causes fit issues in some cases.... some it won't fit, some it will require removing the HD cage and some it will fit just fine. Between the two lean MSI as their BIOS is much easier to deal with than Gigabyte's the the MoBos are of comparable quality. As for the cards, the MSI default fan curves are less aggressive and the fan cut off feature gives it a clear lead in this department. Guru 3D led 1508 to 1501 in boost clock which accounts for less than 1 fps and I'll take the lower noise over the 7 Hz.

I am running Uningine Valley at the moment on twin MSI 970s in SLI and the temps of the two cards are 59C ... so fans haven't even turned on yet. It's only a 1600 x 900 which I use for testing (small and fits on workbench) so I expect I will be able to get the fans on when it's run at 1920.