There are lots of ways to look at it...
Depreciation: 7D is a 4 year old model and bound to be replaced soon. When a "Mark II" comes out, the value of the current model will drop (unless Canon really screws something up and the Mk II is a big flop, which is unlikely). So a 70D will likely hold it's value better. At least for a couple years until it, too is relaced by "80D" or whatever.
Durability: 7D is more heavily built, more metal clad, better sealed and I suspect has a higher rated shutter (150K). Haven't seen any shutter rating for the 70D, but if it follows the theme of the other xxD cameras, it would be a 100K shutter. Might not matter, if you don't use high frame rate a whole lot.
Focusing: Nearly identical, except that the 7D has two additional focus configurations: Spot Focus and Expansion Point Focus. Both cameras have All Points/Auto Selection, Single Point/Manual Selection, and Zone Focus. I'm a fan of Spot Focus for some purposes, and to a lesser degree Expansion Points, so in this respect I'm more inclined to the 7D. Both have 19 cross-type AF points and the Active Matrix focus screen. 7D has a discrete chip driving the AF system (similar to 1D series models) and a pair of Digic 4 processors... but this might not make all that much difference since the single Digic 5 processor used by the 70D fror everything is claimed to be quite an upgrade. The 70D's menu has some improvements that make accessing and tweaking various settings, including those related to AF, a bit easier. 70D has the new version of Micro Focus Adjust, which supports more lenses (40 vs 20), is lens serial number specific (vs lens model specific), and allows two adjustments on zooms. This is the same as on 5DIII, 6D and 1DX. 60D didn't have MFA at all! 50D, 7D and 5DII all have the same, first version of MFA.
Controls: the 7D follows the general layout of the 50D and earlier, and the 5d series, which many feel is a bit easier to use. 70D follows on the design revisions of the 60D, which also have been carried over into the 6D. This is sort of a step up from, but includes some aspects of the Rebel/xxxD series cameras. The most noticeable difference is the "joystick" on the 7D, where the 70D uses a mult-directional button instead. On the other hand, the 70D (and 60D/6D) design makes access possible when using the camera in vertical orientation with a battery grip... While the 7D doesn't facilitate this (5D III got a second "joystick" on the battery grip, to solve this problem.... Hopefully Canon will add this feature to the BG-E7 "Mark II" for the 7D Mark II camera, when it comes out).
Video: If you'll be shooting a lot of video, the 70D is going to be the better choice. It's far more advanced for this purpose than the 7D.
Articulated LCD Screen: Which 70D has, 7D doesn't. The articulated screen should be helpful for video in particular. Can be useful for low angle or high angle still shooting, too. The articulated screen does add some bulk to the camera body, and it might limit screen size and be a bit less durable than a fixed screen. So, much as I'd like it, I don't expect to see an articulated screen on the 7D Mark II.
Frame rate: I really don't see all that much diff between the 7D's 8 fps and the 70D's 7 fps. Both cameras will need to slow down under many common conditions anyway, such as when performing metering during a burst of shots.
Viewfinder: There also is very minimal diff between 100% and 98% viewfinder. In some respects, a less-than-100% viewfinder can be a bit more forgiving, might save a shot occasionally where you crowded the edge of the image too closely.... a 100% VF won't.
Image quality: Minor differences.
High ISO performance: Minor differences.
Metering System: Same.
Wireless flash control: Same.
WiFi: 70D has it. 7D doesn't... 7D relies upon a rather pricey, separate WFT module, which has the advantage of giving considerably greater range than built-in WiFi (approx. 100M vs 30M).
Bracketing: 70D can do up to 7 shots in a bracketed sequence. 7D can only do a 3 shot sequence. This may be very helpful for HDR photography or other purposes. (Note: 70D's in-camera HDR only uses 3 shots, I believe.)
Mode dial: 70D has the "SCN" setting that gives access to the series of highly automated, "point n shoot" style Scene Modes: ala the "Running Man" for Sports, "Mountain" for Scenic, etc. 7D doesn't have Scene Modes at all. Instead, 7D has three user-customizable "Cx" modes. The 70D only has one of those. 70D's mode dial has the neat locking mechanism. 7D doesn't come with that, but one can be added by Canon Service Dept. if you wish, at extra cost (about $100 US last time I looked).
Size and weight: 70D isn't much smaller, but it's a bit lighter. I suspect the 100% viewfinder is what adds weight to the 7D, which actually is slightly heavier than the 5DII.
I don't have 70D. I've been shooting with a pair of 7Ds (and a 5DII) for about four years and have about 100,000 clicks on each of them. I looked hard at 70D, but for my purposes (a lot of sports, wildlife and action photography... no video at all) the 7D remains the better choice by a modest margin. I look forward to the 7D Mark II, when Canon introduces it. For someone else's purposes, it might be just the opposite and the 70D may be a better choice. It depends upon what you shoot, which camera would be a better choice. If you need to shoot video, definitely go for the 70D.
Oh, and when it comes to naming the successor to the 7D... From a marketing perspective Canon would be real fools to not name it "7D Mark II" and not carry over all the good will the current model has earned. Canon marketing is pretty clever, so I supect there won't be an 8D or 9D... It will be a 7D Mark II.
