It’s got to be down to an individual’s experience surely?
10 years ago I was riding a steel ‘hardcore’ HT with Marzocchi air forks.
Today I’m riding a steel ‘burly’ AM HT with Marzocchi air forks.
Granted, I now have more travel from the air forks (twice as much), better brakes (disks as opposed to Vs), better geometry for the type of riding I do and marginally better tyres (I LOVED Spesh Evil Twins!).
For me individually though it’s a dropper post with remote that’s made the most difference. Weren’t around 10 years ago (in any recognisable current form) and until I got one I didn’t know I wanted one. Has changed the way I ride totally in terms of what I will take on and how confident I feel doing things. Not just for steep stuff, but I tend to drop the saddle now for everything other than just riding along or climbing – makes moving the bike around and getting it up, over and down stuff so much easier.
Having said that, can also easily see how for others lights, tyres, GPS, whatever would be more significant.
slainte 🙂 rob