You're best bet is go somewhere that has a bunch of these set up for side by side comparison. Personally, I didn't like the Alesis monitors as well as the KRKs, but you may like them more than I did. I know that some people use the Point Sevens because of their magnetic shielding, handy when you've got them sitting by your computer monitor.
If you do go down to compare, I'd suggest taking your own music to try them out on. You'll have a much better idea of what that should sound like than whatever they have laying around the store.
Also keep in mind that the models we're talking about are passive, you'll need a decent amp to go with them.