Comparing and contrasting former "loves"

I was talking to a relatively new friend of mine last week and he (being a tad bit nosy) asked what was different between my current significant other and the last bloke. If you know me well, you know that my last relationship was, in a word, bad... so it shouldn't be surprising that the new guy has a few things up on the old. His question made me do some reflection though, going back to my first boyfriend, on what the subsequent guy possessed (or didn't).

I haven't had a lot of titled "boyfriends," and actually some of the relationships I've considered most substantial went unlabeled. This compare/contrast concept is actually interesting. For example:

BF 1 to Unlabeled 1
My high school sweetheart and I got along well. He treated me wonderfully, and I never questioned him or his feelings. He was my first love, we were just young. After we broke up, I fell hard for a guy who's feelings I had to question constantly, and who didn't treat me that well. I tried to wait him out, but in the end I got tired of waiting and there wasn't anything he could do to change my mind. He did try though and it's actually one of the things I admire most about him now.

Unlabeled 2 to BF 2 to BF 3
After college, I dated a guy I had a big crush on while I was in school. We re-met a few years later, became friends and eventually began dating. He was what you might describe as the total package, but what I liked best was I could be myself, what I perceived to be my best self around him and he accepted me for me. I knew he was a commitment-phobe and so I never pushed for an official relationship, I just enjoyed his company. It ended on what's best described as a technicality, but we are still friends.

The boyfriend that followed was different from guys I dated before and could best be described as "simple". Nice looking guy, but kind of sheltered and not the sharpest. He was well meaning and tried really hard to be pleasing (too hard), but couldn't hold a conversation about anything outside his realm. Anything but a commitment-phobe, this guy was ready to propose after 6 months, and our relationship ended because it shouldn't have started.

The boyfriend after that was very sharp and we could always talk, but he lacked a sense of humor, passion and a number of other things. I knew him for over half my life, so my expectations were high but the experience was beyond disappointing.

Over the last 10+ years of my dating life, it does look like I have been attracted to people that were fundamentally different from their predecessor, and not always in a good way. Some people stick to a particular type of person - looks, temperament, intelligence... I seem to have gone the opposite direction. If you do an evaluation of your past loves, what do you come up with?

Is there a particular person that you use as a standard for anyone else that you date? If so, why aren't you with that person?