I plan to buy C3 for at least the first year. I am a hobbyist and would love to see some return on my invested time and money but for now I am having way too much fun building games in Construct to consider myself too 'serious'. I have used Construct 2 for about 2.5 years now and in that time I have participated in about 15 game jams solo or with friends doing art/sound/music as well as making countless prototypes and tiny games.
One of the biggest selling points for me is being able to work on the game from a number of different devices and locations easily being browser based and syncing with dropbox. I have started teaching my 6 year old some construct basics on a tablet with this since the touch screen is much more intuitive to younger kids than mouse/keyboard. The current touch controls are a little awkward and I have issues accidentally touching the back button and losing lots of work but I am confident improvements will be made and I will adjust to the controls over time.
I am skeptical of C3 being worth the subscription fee each year but I feel like I have more than got my money's worth from C2 so I will happily sub day 1.