In my opinion it depends who will pay the expenses for the type rating? However I wouldn't pay anything for any of these airplanes.
But I think the G150 is far better experience than the B1900. And there aren't many B1900 around in Europe either.
Consider also which company will give you better terms&conditions and higher salary.
If you're going to business aviation be aware that unless you are rated on CL604/605, or some of the Falcons, or some of the large cabin jets (G450/550, Global) you will always have hard time finding the next job and it can take 1 year or more or eternity to find it (on the same type).
So, if they pay for the type rating and give you a normal salary and you get to fly around 300 hours per year I would go for the G150.
Because there is probably a possibility to do some freelance work on these other 13 airplanes you've found if your company/owner goes bankrupt... There aren't many G150 pilots around that's for sure...
And if you have EASA ATPL I suggest you pass FAA ATP written and get your FAA licence together with the G150 type rating...
Last edited by EDA; 18th Jul 2013 at 20:46.