I wouldn't go that far as to say I know what I'm doing - I know how to make some hash rates and I'm pointing my rigs to some stable-ish pools to rake in some $$$.
The only cards I personally have experience with are the 7950's and R9 280's (which I believe are rebranded 7970's). I run MSI's in one rig and Gigabyte GV-R928XOC-3GD's in the other and the Gigabytes are crap. Already severely overclocked and apparently pretty unstable, I've already got one down and waiting to find a spare motherboard/proc to try and troubleshoot it without taking down a whole 'nother rig for the duration.
But for right now? I don't think there are any good budget GPU's out there. I bought 3 of those 7950 MSI's for $230/each and 3 R9 280's for $300/each and I got damn lucky doing so. If I had to go out and buy a card today, it'd be
a) anything available
b) the fastest thing I could find for the price
Cards are so marked up right now that the barrier to entry and subsequent return on investment takes A LOT longer, sort of where ASIC/SHA-256 mining was a few months ago. Sorry for that bubble burst...
- mike