Well, if you have the money and you want to spend it all on a bike, go custom Ti. Get what would make you happy. If it were me, I would go steel (because, budgets matter a lot to me) and wouldn't go custom. Bikes are very adjustable to different body proportions and you could save a couple thousand dollars by changing the stem longer or shorter, dialing in your ideal saddle height/angle/position on the rails and if you had to, getting longer or shorter crank arms. But that is just me. I wish I had over 8k to get a Moots (standard sized), because I really like how they look and how I hear they perform. The problem I see having with a custom bike is having difficulty selling it, or finding someone to even give it away to when I no longer needed it (ya know, when I am in my grave).

It's all up to you, and your budget though. Someone has to have all the nice, shiny new things!