I don't have a lot of experience with the active (i.e., electronic) earmuffs, but I do have some. Howard Leight model is the one I currently use, and my wife prefers one by Caldwell. Both take normal AAA batteries, and last a good long time. Both are under $50 a pair, very comfortable, with a noise reduction rating (NRR) of around 22 or 23 dB. Perfectly fine for normal small arms fire. If you're shooting a 50 BMG or some other type of magnum cannon with a compensator, you might want to look for something more in the 30 dB NRR range.
Bottom line, I love the electronic earmuffs. I can hear everything between shots, which is a huge safety bonus, and they're every bit as comfortable as the passive earmuffs. Plus, as an added bonus with my particular model, I can plug my mp3 player into them and listen to good tunes while I shoot (keeping the volume at a reasonable level, of course, so I can still hear my surroundings). Some shooting schools require the electronic earmuffs for safety reasons. I'd tend to agree. Get on Midway USA website and check their selection out. You don't have to buy from them if you prefer someone else (you'll probably find a better price somewhere else), but at least they have a wide selection, and you can easily do comparisons based on price, NRR, and other features, and make a good decision.
Last word...you get what you pay for. I'm not saying by a $300 pair of Walker's, but if you buy a pair of $25 cheapos, don't be surprised when they crap out on you.