I do love my SIG-229 .40S&W, I do own a Glock-27 and love it and I have been thinking of buying the Walther P-99 in .40S&W. I also love my SIG-239 .40S&W and my H&K USP .357SIG.
Glock 31 + a factory .40 barrel. Or better yet, just get a Glock 22. Personally, I would get a 23 - it is more efficient size-wise. I have a G22 and I like it. The 23 is on my aquire list. Sig would be my close second choice. I would not buy a P99.