Choosing budget GPU woes

Looking to upgrade my old GPU as its dated, and since I have been tinkering with WPA cracking for fun, I figured I might as well get a GPU that could be used for that as well.

My current desktop GPU gets me around 5000 p/s which seems slow, I tried installing another GPU with a defective heatsink (an HD 5850) which gave me around 50.000 p/s but tempt out after a few minutes.

I am hoping to get something under 100£ that would beat my 5850 significantly and still be relatively silent/cool when idle- preferably with 2 DVI outputs as my old monitors only have that input and I would not have to buy converters.

It seems super confusing that AMD changed their naming scheme, but I found the post in here that somewhat helps with that:

R5 210 => HD 5450/6350/7350
R5 220 => HD 6450/7450
R5 230 => HD 7470
R7 240 => Crippled version of HD 8570
R7 250 => HD 8570
R7 260 => Re-worked HD 7770 with 128 more stream processors
R7 260X => HD 7790
R9 270 => Re-worked HD 7870
R9 270X => Re-worked HD 7870
R9 280 => HD 7970
R9 280X => HD 7970 Ghz Edition
R9 290 => Re-worked and underclocked HD 7970 with 512 more stream processors
R9 290X => Re-worked and underclocked HD 7970 with 768 more stream processors

And a prioritized list of the best GPU's:
1. Nvidia GTX 980 reference design
2. Nvidia GTX 970 reference design
3. AMD R9 290X reference design
4. AMD Radeon HD 7970 reference design
5. AMD Radeon HD 7950 reference design
6. Nvidia GTX 750Ti (only OEM design available, but that's ok)
7. AMD Radeon HD 5970 (only available as reference design)
8. AMD Radeon HD 6970 reference design
9. AMD Radeon HD 5870 reference design

But these are the top notch GPU's and seemingly a little on the expensive side for my budget or hard to find due to age.

My questions are:
1. Should I stay in the AMD camp, or would Nvidia be better for my needs (low price, cool running)
2. Is there a table/chart somewhere with comparable p/sec - I haven't been able to find one
3. Is there a GPU that seems perfect for my needs ?