Personally I'd go with the Cutlass because it seems, on paper, that it is a decent fighter, you can have a co-pilot and you can take part in other aspects of the game should you change your mind later (Keep in mind there is a Hornet model with two seats as well.) But, you can always just try to buy a second ship later down the road in game or by pledging. So I wouldn't feel pressured into making a decision you're not sure on.
That said... Get ready for me overtyping random details like usual.
Keep in mind I am not trying to dissuade you from picking the Hornet, as I'm definitely wanting to pick one up as well.
The Hornet being a strict fighter is not a bad thing at all. It's excellent for PvP.
The whole thing about Star Citizen is that it's a Space Simulation. And with the direction they're going with the game, you'll have to make your own money by doing a variety of missions which will be given to you by NPCs, comissioned by the population or entirely up to you seeking your own fortune. The concept of the game makes it hard to commit to a specific gameplay style. It's a very much self driven concept, at least until we have a better understanding of what exactly we can do in the game and to what limitations.
But that's another point. So far it's all concept. We're still a long ways from having an official structure of how things will work and how you will make money in game. Personally, I talk about it a lot so when there is a concrete structure I can implement my own faster. Plus it's fun as all getup to talk about.
If you think that you'll only do PvP, why not get a Hornet and give yourself a leg up on the competition? If you're still on the fence, go Cutlass or Avenger. For the time being, you can resell your ship back to the devs for equal in game credits and just apply it to another ship. You'll have to wait 24 hours after purchase though, and I don't know how long you'll be allowed to do this. You might be able to forever.
So, with all that in mind. If you really don't see yourself doing much of anything outside of fighting, go Hornet. If you want to do other things you could go with the Cutlass. Or even the Avenger, as it also has storage space and seems like it's a potential fighter. Or the 300i since it has storage as well.
But it sounds like you really want the Hornet for now. I went with the Freelancer at first. Then I couldn't stop thinking about the Constellation, so I sold my Freelancer back to SC and purchased the Connie. I couldn't be happier now. But now... I have the upgrade bug. Like when you buy a new GPU. You next want to upgrade your... Uh.. CPU cooler. Then add memory. Then an HDD. Then you want a new case... God... I'm a monster....
I need to choose between the Cutlass and the Freelancer. I think the freelancer is better for me.
My goal is the Starfarer, I just wish I had some friends who are into PC gaming, it would be great so split a Starfarer with them.