I have the Braun Xpressive (the pink one).
Amazon.com: Braun SE7280 Silk-Epil Xpressive Epilator Body System, Corded: Health & Personal Care
more specs can be found at the link above
I originally wanted one that can be used cordless (mine is not), but after using mine, i realized that i would not want one that is cordless just because i'd be pissed if it ran out of battery. plus when i'm using it, i'm always near an outlet. so if you're always gunna have access to an electrical outlet, then a cordless one wouldn't really matter for you. plus the cord is long, so there's no need to worry about it not reaching where you want it to.
as for the numbers of tweezers, the higher the number the more hairs it's gunna pull out at once. so it will lessen the time it takes to get hair free. which is a plus.
also, you may want to pick one that has multiple speeds. the higher the speed, the quicker it's gunna pluck out the hairs which i think will lessen the pain. the slower you pluck out a piece of hair, the more you're going to feel the hair coming out of you. if you get one that has no speed options, i'm afraid it might make it hurt more.
mine also has a spot light that allows you to see where you need to epilate. the light will reveal hairs that are hard to see so you can get everything. i think it's helpful especially if you're somewhere that does not have great lighting.
i've had mine for a few months, and i love it. plus it has a trimmer and shaver attachment!
HTH!!