It's not as simple as EITHER/OR. The rechargeables have their own PROs and CONs and likewise with the disposables. The trick is to know when to use what and understanding the strengths and weaknesses of each kind of batteries.
Assuming that you're primarily interested in "AA" and perhaps "AAA" rechargeable batteries for photography related devices...
For flash unit, I'd recommend using the highest mAh "AA" Nimh rechargeables (like Powerex 2700's) for intensive, one time sessions, such as weddings and other events for greatest number of flash pops. The disadvantage with such high mAh rechargeables is that they have a faster self-discharge rate, especially as they start to suffer from memory effect from repeated use. You'll end up having to recharge right before each use with such rechargeable kinds. For non-intensive, intermittent use where LSD (low self-discharge) batteries have an advantage, I'd recommend eneloops. For flash use where fast recycle time and the number of flash pops are crucial, both rechargeable kinds easily beat any brand of alkalines out there.
For low consumption units like PWII's and other similar devices, I'd use either the best "AA" LSD (eneloop) rechargeables or alkalines. Here, alkalines might have slight edge over rechargeables, except it's not as "green" and they could damage the units due to leakage if unattended for a long period of time and under certain temperature. As for "AAA" batteries for TV remotes, wireless PC mouse, house fire alarms, and such, I recommend disposable alkalines for greater duration over their rechargeable cousins. But then you'll have to decide based on their own pros and cons: rechargeables are more economic and "greener" but a hassle of having to recharge very frequently, whereas the disposable alternative has an advantage with the duration of effectiveness but definitely more economical and green.
I'm sure things would change as battery technology advances, so my recommendations are for the current status quo.