Striker Fire Handguns?????

[West Side Willy]

Thinkin' about getting one of these striker fire guns and taking the 1 day transition course. What do you guys think of these type of weapons? Also, let me know any pros and cons to the Smith & Wesson M&P, Glock, and Springfield XD models. Not sure which one to get. Probably gonna go fire all 3 and see which fits me the best...
One final thing, need to figure if I want a 9mm, .40, or .45. Been hearing alot of people going w/ the 9mm because of the increased velocity. But I'm part of the old school philosophy of a bigger hole is always better, lol. Let me know what you guys think, appreciate it.

[Blue Shirt]

I personally carry the S&W M&P .45ACP.

[twin]

I like the S&W M&P .45. shoots nice and leaves big holes

[MikeMoon01]

I have a little one 9MM but now I have shifted my accommodation (I left a street and Now lived in a park home) and I feel more need a gun then before that's why I am looking for to change it. so you please suggest me what I should have now. your suggestion would be greatly appreciated.