Ti vs steel....I've had off the shelf and customs of each. I don't really prefer one material over the other.
Concerning ride quality, what it all comes down to is what diameter tubing the frame is made from (larger diameter tubing gives an exponentially stiffer frame), tubing wall thickness (thinner is lighter and gives a more compliant ride, though this is far less important than tubing diameter).
I like ti because it won't rust, there's no paint cost, nor paint to scratch Also, for the same "planing" ride quality, a ti frame will be more dent resistant.
I like steel because it can be less expensive and I like the look of thinner tubing and steel will still hold up well for a very long time. Builders like Speedvagen and Gunnar do make beautiful bikes, but if they are using larger diameter tubing - which it looks like in their pics, then they're going to ride pretty stiff.
I'd suggest that you look at smaller steel and ti custom builders because you might find a better value and a builder who will build what you want and not what they want. I went with Mike DeSalvo for a ti frame last year. He builds custom ti and steel bikes and is commonly featured at large gravel bike shows (he's an instructor at United Bicycle Institute in Ashland, OR). His prices are very reasonable and way less than the big name players like Moots (you're probably paying an extra 1-2k just for the Moots, Speedvagen, etc name). There are probably a couple of top notch custom builders in your area as well - I thought I saw an article on a builder in Arkansas or Louisiana this spring (on Radavist?).
Another idea is to get a custom steel frame built by someone local or inexpensive and ride it for a year or two to get an idea of what you like and dislike about it in terms of geometry and sizing and looks. Then take that info with you and incorporate that into your more expensive dream build bike. You'd hate to spend 5k on a frame and have it not be perfect.