I use Lelo Luna Beads mini. But regardless what you use, you'll probably want to start of with smaller.

I can, strangely, take bigger anally can I can vaginally (weird, huh?) so these MIGHT be too big for me after all... Onwards with my search.

Smaller exercisors are actually more difficult to squeeze.

I know this sounds extreme, but have you tried asking your doctor? Sometimes muscles can get permanently tensed and weak at the same time. This makes it hard to do an effective kegel because before you can strengthen you actually have to forcibly relax the pelvic floor. For incontinence issues, a doctor is definitely worth contacting (or a friendly neighborhood sliding scale women's health center).

The set above is good, though. I don't have it but have heard good things. My favorite kegel exercisor is the energie, which is a cheapie barbell. I thought it worked better than balls by a long shot.

I've been doing kegel exercises with toys for over 5 years now. I've used many different types and I HIGHLY recommend the Luna Beads, the mini set especially. They're a nice in between size from classic benwa balls to something like smartballs. And, with those, you can start off really small, like with one ball and work your way up!