Stick to what you both enjoy. It's obvious your passion is the medieval period, and specifically the Eastern crusades. That said, spreading out into the earlier dark ages, or later renaissance, or to more exotic medieval locals wouldn't be to far off the mark.
But to start producing napoleonic, WW2 or ACW, would be a mistake. There are already many others companies, small and large who do those eras. As it stands now you fill a niche market that no one else is doing.
BTW, I noticed that Michigan Toy Soldiers has both your Zvezda Ship Crew, as well as the plastic Medieval Army on the March set in their 'coming soon section. This is great news for me, as I don't have a PayPal account (because they don't except 'gift card' credit cards, while most merchants do). They also have all the new personality figures listed as well. I think you'll see a spike in sales in the US because of this.
Re: Re: If we were to do one personality figure...
I won't say nothing in particular as no many chances to see what I'd like, as usualy not popular and not so commercialy convenient, but never mind, I can manage myself... even if my resin miniatures are much poorer than your real great ones!
Just one consideration of what usualy is missed in the range, I would choose to make a female personality, or a male one overweight, as it seem to me there's a total lack of such subjects.