Yeah, I always judge software by the release number.

Fact is, Apple continues to release updates to Aperture 3 and, for me, the app works extremely well. In fact, because the software is sold through the Mac App store it's advantageous to users that Aperture stay at 3 since we're getting all the updates for free. I'm sure 4 will be a paid upgrade. Sure, there are things I would like that Lightroom already has, but I'm sure the same can be said about some of Aperture's features too. As for plug-ins, all the ones I use regularly (Nik and OnOne Perfect Photo) work in both. I haven't seen any plugins that work in LR and not Aperture, but I wouldn't be surprised if there were a few.
To the original poster, I would use Lightroom simply because it's what you know and already have invested time into your library. I'd probably also try out Aperture. I've got both, but prefer Aperture. YMMV. Adobe makes great products, I use Photoshop all the time with Aperture, and continues to update their product number every time they do. That's fine, but don't judge the software by the release number. That's just dumb.
Rob