Web apps on VPS sounds like something fit for micro or tiny instances, in which case a month pre-commitment might actually be cheaper if you look at OVH's Kimsufi programme: https://www.kimsufi.com/en/vps-ssd.xml. These are cheap, but in my experience reliable (after multiple suboptimal experiences with DO) KVMs.

While KS is probably more important for EU customers, the KS-VPS line has three regions to choose from: Gravelines (Northern France), Strasbourg (Eastern France) or Beauharnois (North-America). You can also DIY your own cloud with https://www.ovh.ie/vps/vps-cloud.xml, though I've never tested this.

Personal point: I may be very old-fashioned, but after using GCE and AWS for various tasks, I still prefer the transparency of pre-committed billing. E.g., I don't know if this changed by now, but I ran into dozens of inexplicable administration errors with GCE, to the point where I couldn't manage my own projects anymore. Plus, after creating billing details, I couldn't detach my credit card from the platform. The only way around that was to disable all projects, but that still left me with an uneasy feeling.

I don't have automatic billing setup for KS/OHV. I get billing reminders 30/15/7 days before each cycle and authorize each payment.