I use the Crosman powerlets, work good, never gotten a dud. I have also used the "Brass Eagle" brand and they were ok too, but they have a sticker on them that tends to make the powerlet get stuck in my guns....stick to the Crosman ones. I've never tried Daisy or anyone elses, but suspect they are "ok" also. The thing with CO2 is that it is liquid and at a constant pressure at a given temperature...so you aren't going to get "a real extra powerful" one, just one that lasts longer or lasts shorter. Your main concern is getting "clean" ones, and I avoid the ones with stickers. Also wipe them down before putting them in your guns so you don't get junk in your valve or seals. As far as purity of the gas inside them from brand to another, I couldn't tell you, but I have had no problems with the crosman ones. Hth!
