I've looked at both (but didn't drive the e-Golf). As stated, the e-Golf has a lot more room - I had to slide the driver's seat forward from the aft stop to position it correctly for me, whereas every Asian car I've driven or owned for the past 27 years has been at the aftmost position, with me wishing for more (34" inseam). Cargo space with the seats up is also greater. The Spark has just enough legroom in front for me, especially given that you can't drive it for more than an hour or so non-stop, and cruise control helps. But I wouldn't want to put any adult or teenage child directly behind me for more than a few minutes in the Spark, while the e-Golf wasn't a problem - my knees weren't touching the front of the seat nor did I need to splay them out; in the Spark they were touching even with my knees splayed out, in fact they were making solid contact.
The e-Golf definitely has a more upscale feel, and will be appreciated by those who, like me, prefer standard analog gauges and real switches instead of touch-sensitive screens that require you to take your eyes off the road to adjust the HVAC system or similar. In short, it's a typical no-digital nonsense European car. Of course, the Spark also has three dial HVAC controls, so call that a wash. Judging by reviews, the e-Golf also has the best overall driving qualities of the affordable BEVs, although the Spark is faster. And Tony Williams drove an e-Golf on his standardized test (62 mph cruise control, no wind, ideal conditions) for 100 miles, slightly exceeding the 2014 Spark EV's range on the same test; the 2015 Spark, with the smaller battery and shorter gear ratio, only managed 89 miles during the same test, done simultaneously.
It's really just a question of what you're after and what you value. If you just want the smallest, lowest cost commuter that you will normally not need to carry more than one other person and some stuff, the Spark's good. But if you routinely have to haul people in the back, or lots of stuff, then the VW is the way to go, and it's also more refined. And for a good middle ground (if it's available in your neck of the woods at the moment) I like the Kia Soul EV, which had about 1 mile more range than the e-Golf on Tony's test, costs about the same, and isn't as boring looking as the e-Golf, for those who care. Hard to go wrong with any of them, I think. Edit: Although VW's Car-Net seems to be really buggy and hard to use. Whether that's just initial teething problems or a long-term issue remains to be seen, but there are a lot of complaints about it on the e-Golf forum. 2nd Edit:Oh, I prefer cloth seats to leather or vinyl, so the Spark 1LT beats out the e-Golf on that score. Of course, seat covers are available.