Currently you'll find both versions to be mostly alike, but GMS 2 versions offer many quality of life improvements missing from GMS 1. You can see the full list of updates here. The difference will only get bigger over time as future updates to VNgen will apply to GMS 2.3+ exclusively.
Permanent GameMaker licenses are still available through Steam for now—I would recommend looking there if you aren't keen on a subscription. Alternatively, you can use the free tier as long as you wish and subscribe for a month when you need to export a finished product.