The newer ones are good, however the series has turned into more action oriented than "survival horror" (which was just a marketing term Capcom made up anyway). I love RE4 and RE5 but they are clearly different from the original RE through RE:Zero.
Personally I prefer the older ones but I understand why they changed it up. By the time Zero came out, the formula was getting a bit stale (though REmake on the GameCube is awesome) and Zero's sales were pretty flat and the game got mediocre reviews. And I actually agree with it, I didn't think Zero was nearly as good as it could have been.
RE2 and REmake are probably my favorites, followed closely by RE4.