I've recently decided to bite he bullet and give Lightroom a proper try. I've been using Apple's Aperture for about 7 years since Aperture 2 but the lack of investment Apple have put into the product has left many Aperture users frustrated, myself included. I've initially looked into it for my Landscape photos, especially for lens corrections against my 17-40L but will keep family photos in Aperture.
Anyway...... tethering. I've used Aperture for tethering in the past (the ability to take photos and immediately have the photos transfer to a USB attached computer. For me that's my Canon 5D Mark ii with a 5m USB cable connected to my Macbook Pro. I have used Aperture for this in the past and I have to say it's been with some success. I find it very useful where you're trying to fine tune a pose (like a dancing pose).
The features of both products seem quite advanced - I particularly liked the ability to immediately process with a preset in Lightroom .... HOWEVER, with Lightroom the whole thing locked up on me on a few occasions. Halfway through the shoot I was unable to take a photo as the camera was showing 'BUSY'. It was struggling to get the photos across into Lightroom and I was having to wait and wait. In the end I decided to disconnect the cable to keep the shoot going.
By comparison, with Aperture it was very quick - almost instant. So which one am I likely to turn to the next time I do tethered shooting - Aperture.
[This was Aperure 3.5.1 and Lightroom 5.4]