they're all good and much improved over stock. You can also get your stock shock revalved for a much better improvement. Call Elka Shocks on that. As far as shocks, just get what you can afford, you get what you pay for. Works are inexpensive and much better, Custom Axis are great and more expensive, and Elkas are pricey and supapimp. But they are ALL going to valve it specific to your riding style, application, weight, and so on. So there's not a bad "type" of shock, it's all on price.
Searching shocks will lead you to more info.
Great reply!! Just thought I would add that I had my rear shock reworked for my -2 swingarm by santo derisi and it feels 20X better than an improperly setup PEP my buddy has on his 'shee. I believe it ran me 250$. It's a perfect choice for those who don't have the cheddar for full aftermarket replacement.
Edit: BTW: It dropped my rear end about 2'' so now it sits level w/ the front end... which has elka dual rates and +2+1 arms on it. My 'shee measures 8 3/4'' from bottom of peg to ground without anyone sittin on it .
Mike