Defender Decision

This is my first post but you folks can give me some needed advice. I am looking at adding a Colt Defender to my collection and I shoot all guns I own except one (Gold Cup Commander). Because I shoot my collection the gun can be new or a used cherry. There are four choices. The Defender was made in both 40S&W and 45acp. I am a 45 guy (see handle) but thought the 40 would be tolerable and might be a bit more collectible long term (although I really don't see any of these mass produced guns setting price records). The other variable is the wedge shaped (Novak looking) sights which cosmetically don't seem "right" on this gun vs the 3 dot billboard rear, the more recent addition. There are the 4 choices, 2 possible calibers, two sight styles, please give me some points to consider along with opinions on this gun. Thanks, nice to be here wih you. Ed