The coupe would be better as you could stuff batteries in the boot/trunk. Also, the loaded weight is less.
I considered doing this at one point but decided I'd end up with a car that wasn't one thing or the other.
If you are on the beginning of the learning curve of electric tech you may consider building an electric bike first. A bicycle and an electric motor is a match made in heaven. Add a few hundred watts to a bike on the hills and riding becomes a pleasure. You can stretch the battery time by peddling more, when it runs out peddle home. I'd suggest a mountain bike with a 'center drive', keep the weight low and centered and mountain biking is a blast.
I use lithium LiFePO4 batteries. These are the least likely to burn your house down. Endless-sphere.com is a good forum.