I have the Spigen Rugged Armor and the Speck Presidio. To me they are completely different cases. The Spigen is nice, slim and on the slick side. When using the phone, it has a nice look to it.
The Speck is very grippy with the grooves on the back, a little more bulk to it, and the front lip isn't quite as "refined" as the Spigen.
For me, the Speck is back in the packaging and the Spigen will stay on the phone.
I ordered the Rugged Armor for now, it's one of the few TPU cases I've seen that's A) in stock and B) not totally bland. Even the cheapest cases only seem to be available in odd pastel color choices (or plain black)...
I'm waiting for Diztronic to give an ETA on their Androidified TPU case (check their site), used similar ones in red with my previous two phones and was very happy with them. I'm not a fan of hard back cases, seems like that'd do a worse job of absorbing impact and it just adds bulk...
The Spigen Neo looks interesting, I've never used a hybrid two piece like that... But it's only being made for the Pixel XL.
Caseology's similar Parallax got excellent reviews for other phones, hopefully they make it available in other color choices but black once it's in stock...
Some of the color choices they offer for the iPhone/Samsung look super sharp. I'm just concerned about the way that plastic rim could change the feel of the phone... The best plain jane TPU cases retain the phone's natural feel pretty well.