Are there any decent Tegra4 smartphones coming out ? Apart from some chinese smartphone maker (ZTE or Huawei ) , no other company is making a T4 based smartphone. HP is bringing a Tablet, but HP doesnt has had much success with the mobility market. The T4 is supposed to be hot and power sucking. Buying a T4 smartphone should be in your low priority list.
Depending on your country, you can get a Exynos Octa SGS4 . But wait atleast for AnandTech to do its review. The one that came out some time back was for the S600 version. Plus, Galaxy Note 3 is supposd to have the Octa exynos by default, IIRC.
S800 , well some phones have been rumoured or announced to have this chip, but the release dates are in mid-late Q3, IIRC.
Really, you cant do much wrong with a SGS4 or a HTC One. They are the best options right now. And to be frank, in the smartphone market, whatever you buy will be replaced by a faster verion in 6 months
I wouldnt recommend playing the waiting game here.
Hope this gives you some perspective.