I'm a Unity player (or rather I was, I'm now based on Chaos). I believe I'm fairly typical of our guild in that I have 1 or 2 bipeds, a dragon, a biped plot and a lair. I paid 2 subscriptions for this.
I don't NEED 5 character slots, but I don't mind having those as an option (mules are always useful).
My primary aim in this game is building. It's the one thing NO other game out there has (EQ2 has nice housing, but it's instanced, and you don't build it)..
I'd happily pay $14.95 per month for a standard sub but I'd like the option of adding an extra plot (as so many have said). Consigner limits - well, I may be the exception - I hardly ever use them! That said I know a lot of people who do, so let the "basic" accounts have them - you're trying to hook them on the game, so let them experience the full flavour. Limit the basic accounts to the 25x25 plot size - no serious plot builder really wants something so small.. but don't stop them having plots - they need to experience this too, and someone who gets hooked will upgrade..
Oh, you haven't been clear - are you ALLOCATED plots? or can you pick where you want to be? Do guild plots count - what happens if you are allocated a plot miles away from anyone in your guild? Can you sell it and get another?
Have a donations option too - some of us want to help support you, and personally I wouldn't mind paying $5 or more extra a month to aid you get off the ground at least, but I know I'm in the minority of those who can afford to do it..
I'm really excited about Horizons becoming a viable game again - and want to start saying to people "come back" - or "come try this" rather than what I've had to be saying this last year "love the game, shame about the support and the no development problem.."
I definitely would pay more for a BIG plot, or a combined lair/plot.. even an ancient subscription purely for this!
Sarah