Hmm, no dudes talkin' about dude toys on here. Guess I'll break that. So, I have Tenga's Flip Zero model onahole. I must admit, it's pretty great. The first few uses were pretty eh though. It was entirely too tight and took some loosening up, which occurred after a few uses and a lot more lube (for the record, you will need the lube for every use.) Since penis size actually matters here, I'm six inches long and 1 3/4 inches thick. The entire inner chamber runs 6 inches and can barely take in my entire penis. Given my width took some time for the toy to adjust to, if you're larger than me you might run into problems with this series.
The great part about any of the flip models is they open up in a clam shell fashion. This makes cleaning very easy. Unless you like things a little cold, you should warm it by submerging it in warm water before you add any lube to them. There are different models, usually designated by color. The primary difference is internal, with different massage textures. The Flip Zero (which I have) is further differentiated by having an exterior that's a lot less plastic and more of the silicon, which allows you to apply pressure all along the outside, while the other models just have three push down buttons for pressure applications. The silicon is shaped in such a way that it forms a one way valve at the end, so that when you either squeeze air out of the toy or push it out via filling it with your dick, it create a vacuum and the toy clings to your penis. The toy isn't really for beating off, but more so massaging the dick. Since there's different textures lining the entire inner chamber, you'll probably find certain spots of the toy you like to really rub your penis with more than others. After using the Flip 0 model, I think I'd probably enjoy the red model (mostly based around having a ribbed interior) but don't plan to be buying another one anytime soon. The older models are $75 a pop from the official manufacturer. The Flip 0 models (it seems they've expanded this series) run for $100. You can buy from other retailers for cheaper, but these ones seem to come with reviews that concern breakage of one sort of another. It could be defective toys, but it could also be the users being too rough with them. There's a new vibrating model, but it sits at a wopping $200. The site lists the toy is good fo 50 uses, but I honestly feel you can get more out of it so long as you take good care of it (I haven't counted my own uses, but I may also uses it for an hour or two at a time. I don't know how normal that long of use is.)
All that said, this is the only onahole I've ever had, so I can't really compare it against anything. But it feels great and it's pretty easy to clean.