We went a little off tangent on the Archive release thread in regards to this, and while @Jerseyfornia's original question was to the ladies of the forum about when the peak of physical sexuality was, I thought it might be ok for the male demographic on here with what they think his peak(s) of coolness are.
To start us off, I'm gonna go old school with a good old fashioned list. And to make it more enjoyable/less tedious, here are 18 photos representing 18 eras (kind of) - in reverse!
18. Early to mid 2016 - I still don't know if it's the haircut, the lack of facial soul-patch, loose clothing or a combination of the lot, but something is very off about the way he looked here. Thankfully as the year progressed he changed it up for the better, as we'll see later on.

17. 2003 - I think this is only second worst for me on account of not being a fan at the time, but aye, speaks for itself really.

16. 1976 #1 - There are two sides, I believe, to his appearance at this stage of the Chicken Scratch Tour, and this is the lesser of them. By far.

15. 1995 - 1997 - Honestly, there's nothing wrong with his Joad Tour look, but I wouldn't call it 'cool' in the typical Springsteen sense.

14. 2005 - He also looked similar to this in 2006 (not included) and from 2007-08 (included), but this is #14 because his 'coolness' was affected by what can be called a bit of crankiness across the Devils & Dust Tour.

13. 2008 - As can be seen, quite similar to the above and the culmination of Bruce's pre-hair transplant days. Given #13 because rock and roll Magic Bruce is cooler than 'cranky' D&D Bruce.

12. 1992 - I was interested reading JF's praise for this era, mainly because I've always felt he was just on the brink of looking like he was having a mid-life crisis with his get-up. (I guess that was just the early 90s in general, though?)

Eleven (typing it out as 11 is turning into 1). 2018 - The Broadway look is the antithesis of early 2016. Cool short hair, simple black t-shirt and jeans. What else can be said?

10. 2000 - Tbh I don't think the picture does it justice, but we've all watched Live in New York City enough to know his look in mid 2000 was class. There was some questionable facial hair and shirts in 1999, but MSG for the win.

This is a long OP, so I'm gonna continue the rest of the top 10 in the comments. Hang tight!
I saw this photo somewhere and thought it was a very appealing look for Bruce.
I really didn’t like these beard goatee things when they first came out, but they grew on my over the years.