I've helped quite a few tech startups (mostly in travel & SaaS) nail down their value propositions, especially as it relates to copywriting & conversions.
Just a guess, but could it be that you're focusing too much on differentiating based on your website's "features" or what it does?
If the core of what you offer isn't all that unique, try looking at other ways to differentiate. For example:
- customer service (Zappos)
- world view or business POV (Tom's one-for-one strategy)
- personality (Mailchimp)
- product design
- the audience you serve (niche out)
- how your website is created/run
Not all of these type of differentiators will be "game-changing." But if what makes your service/website unique resonates deeply with your target audience, maybe you don't have to be a "disruptor" like Uber or airbnb.
Tough to say without knowing what industry you're actually in.
If you want to chat, feel free to contact me.
Hope this helps.