I'm very curious about which option is better for the company's strategy view:
You didn’t tell us how similar these three groups are. It’s possible they’re very similar. In which case you can start with one general product that meets the basic needs of all three of your target groups. Once you have that basic feature set, you can start incorporating advanced features into your product that meet the needs of one of the three groups. Spin that off as a separate product. Now you have two products, one that meets the basic needs of two of your target groups, and one that is more specific to the third group.
If your three target groups are so different that it will basically require three completely different products, then focus your efforts on one group at a time. Going this route allows you to focus all of your resources on that one market, and thus increasing your chances of success for that one. Once you’ve succeeded in that market, and have money coming in, you can start working on the second market. I’m assuming that as a startup, you don’t have a ton of resources, and if you try to do too much at once, you run the risk of developing three mediocre products that nobody wants.
Regardless of which approach you take, make sure your design is modular, both in software and hardware. This lets you reuse a lot of your previous work when moving from one target group to the next.
In my case, we opted for the second approach. We’re developing a security product for web browsers. There are several web browsers out there, but we decided to focus on supporting Firefox first. Once we’re successful with Firefox, we’ll start developing a separate product for one of the other browsers. Hopefully, we’ll reuse a big portion of the first development.
I don't know what you product is, but if you are small company (one developer) then probably it is better to start with one product. Then, if there is particular interest in splitting this product in two or more products, you can do it.
Form the marketing point of view, 3 landing pages is good idea, targeting different way of using the product.
I always try to resist the temptation to split my product on 2 products. The reason is that I know that it will be very difficult to support both products and continue to develop them with the limited time resources.