I'm partial to core only blocks as well. As for qhich one...honestly, they all cool the GPU pretty darned well so I would just get the lowest restriction block you can find. I have an old DangerDen maze4 on my 4870 and it keeps it about 35C under load.
Back when I had my 4850 it was vmodded 1.39V 880mhz and temps still did not go above 35-38C.
As for the VRMs... If your card is of reference design then I recommend a Zalman RHS50 VRM sink. I have the 4870 version and it really is quite good, keeps my VRM temps under mid50s during full load.