For the PS3, it partially depends on the model you have. I'd also stress not to pay too much, as performance gains between different drives is going to be pretty minimal overall, so your main concerns should be heat, noise, and reliability.
See here:
http://en.wikipedia.org/wiki/PlayStation_3_technical_specifications to identify which specific model you have, and look at the section for yours that indicates the CPU and GPU process.
90nm CPU + 90nm GPU: Older fat models
- Go with a 5400rpm HDD or an SSD, as these models tend to run warmer and suck down more power than later ones.
90nm CPU + 65nm GPU: Early slim models
- I'd still probably go with a 5400rpm HDD or SSD, mainly out of concern for noise. These run more efficiently, but not drastically enough to justify the added heat or noise from a 7200rpm.
65nm CPU + 65nm GPU or better: Later slim models and 'super slim' models
- Go with a 7200rpm or SSD, depending on what your budget can handle.
As far as what to buy among the various types, I'm extremely partial to certain brands, but the ones below are all currently in use here.
5400rpm: Western Digital Scorpio Blue series. I'm using a 500GB with my fat PS3.
7200rpm: Western Digital Scorpio Black series. Two currently in service on my desktop/gaming PC.
SSD: Samsung 800-series. I'm running a slightly older 840 Pro as the OS drive on my desktop. Probably overkill for a console, and not cheap, as it'll run you around $160 for 250GB and $300'ish for a 500GB.
As for the 360, meh. Microsoft made the whole process into a mess of exploitative nonsense, so you'll pay way too much for an 'official' drive, then go through an idiotic "license transfer" process via the website that may or may not let everything transfer over, and if you don't have an external hard drive to backup to, you'll have to pay for a transfer cable. If you're handy at all with hardware, I'd look to go the DIY route, but if not, try to find a cheap, official 320GB, be done with it, and hope you never have to muck around with that stupid crap again.
