Row 1
So, top row I take Unholy Blight. Great in situations with large groups to spread your diseases easily without Pestilence.
Row 2
2nd row down, I take Lichborne for extra healing and put it into this macro:
cast Lichborne
cast [atsymbolMyname] Death Coil
and spam it for healing when I have runic power. You could also take Purgatory incase you drop really low and think you can be healed out of it. If you're confident your healer is good, take Purgatory, if not, go Lichborne.
Row 3
3rd row down is tricky. I take Asphyxiate in 2s and Chillblains in RBGs/BGs. Asphyxiate is an improved silence AND turns Strangulate into a complete movement impairing effect. Chillblains turns your chains of ice into a complete movement impairing effect AND gives Frost Fever a slow. This makes Howling Blast even better for AoE and a bit more effective for single target. Up to you depending on situation.
Row 4
Next row, Death Pact. Great heal and only a 2 minute cooldown but does require a ghoul. I have had this heal for in excess of 300k before but sometimes it won't do as much. Majority of the time hits around 150k-200k heal at 90.
Row 5
Below that, Runic Corruption. Brilliant for rune regen and just an overall great talent. Very useful in PvE and for me, very useful in PvP too. Blood Tap is great if you need runes on demand or if you're needing a lot of AoE so you can rune regen/howling blast spam but I personally prefer Runic Corruption.
Row 6 - The Hardest Choice
Last row is the hardest one. Gorefiends Grasp is excellent in large fights in BGs or RBGs. For example, Lumber Mill on AB. Grasp all into a group and get an Ele Sham to Thunderstorm off the edge. However, it isn't so useful in arenas unless it's a 3v3 or 5v5 situation, in which case, other talents would be better. This brings me on to Remorseless Winter. I have found this to be excellent in large fights as it is an AoE stun, kind of like Capacitor Totem. It adds stacks of movement slowing until it reaches around 75% I believe, at which point it puts the target into an ice block stunning, silencing and freezing the target. Very useful in all kinds of combat, even a 1v1 situation as it will affect the one target in the same way it would affect 5 etc.
Now if you do a lot of PvP, or even a little, you will know how useful a trinket is. Desecrated Ground, the 3rd talent on the bottom row acts like a second trinket. It can be used in any loss of control effect and will break you out of it. Very useful in 2v2, 1v1, 3v3, 5v5, 10v10 etc. Great in every situation but you have to consider which would be more useful for you as a player. This row is easily the row that is most about personal preference. Try them all out and pick your favourite and stick with it!