When not OCing I would recommend the cheaper versions from the brands with a good reputation among OCers. If OCing use the brands and versions the OCers use for that particular board.
While building and testing new computers for allmost 1.5 years I had to RMA 15-20 % of cheap non-brandname RAM but less than 1% of brandname RAM
I've given up on generic unbranded RAM after similar bad experiences. Unless you are prepared for the cost and time of returning bad RAM I would leave well alone. I did recently see some unbranded DDR2 PC5400 that was ridiculously cheap and a part of me was tempted. But, the cheaper the RAM the worse it probably is.
As for tighter timings and higher RAM speeds, if you look at benchmarks you see that you get very little back in return for the high prices of 'exotic' RAM. Personally, I think it's mostly a waste of time and an Ego trip; the money is better invested in other components. The one time it makes sense to me to buy fast RAM, is if it means that you can overclock your CPU more. This is usually only true for extreme overclocking I think, as usually changing the memory divider means you can get away with using PC5400.
Here's an idea; when you place an order for memory order a cheap generic RAM and a value branded RAM. If the generic RAM fails RAM testing then simply return it. If it passes then send back the branded RAM. In the UK you can do this with no questions asked and mailing RAM will only cost you pence.