IMO it's still just a matter of how you work: if you like Lightroom's structured approach, you'll prefer it over Aperture. If you prefer Aperture because it doesn't lock you in its workflow, you'll get Aperture.
Lightroom has caught up in some regards (e. g. multimonitor support, now you can use two screens), but it still doesn't have any vaults, for example. On the plus side, it has more advanced retouch features (compared to Aperture), e. g. Dodge and Burn works non-destructively (as opposed to Aperture).
You can download trial versions of either app. You will have to try both yourself.
Disclaimer: I don't like Lightroom's UI, as a matter of fact, I strongly dislike it. But that's just me.