My Kegal exerciser of choice right now is the Jopen Vr1, you can either put it in exercise mode or manual mode. It has Intense Incremental Speed Control which means you can really tell if you're exercising the right muscles or not. I just got mine 1 week ago and though the controls were a learning lesson I have them down now. Unless you regularly measure that you're tightening the right muscles with your fingers, I believe this is the way to go. Oh and I have not been able to walk around with it yet without real tight panties. Gravity easily pulls down on the weight of them. Perhaps when my Kegals are stronger I'll be able to do so. All in all I still recommend it and right now Jopen is offering free lube with their products.
I have the Luna balls (large), Smartballs, Blue glass and Clear/Pink glass eggs but with none of these can I tell if I'm squeezing the right muscles. Hope this helps.