for the money, the 45P is a no brainer, they are all good, for the most part pretty excellent but they get expensive and used prices often aren't that much lower.I was coincidentally looking at the 45 today! I would love to have a nice 'walkaround' for when we take a weekend off with the kids. I always have an equivalent of 35mm and 50mm in all my kits so that would compliment the full frame and apsc gear I have.
the 33x44 sensor changes things in regard to focal length. I thought I would want/need 21, 45, 90 but now I have 21, 30, 45, 65 and got the 120 since I was able to sell the 90 to friend who now also has the 30, 45 (and now 90) the 30 and 65 were the real surprise to me, never thought I would use those so much.
but the 45P is the perfect starter, walk around lens and a real bargain at the price!