I use textile for work and leather for pleasure riding, but each to their own, as long as it’s protection
There are some very cool waxed cotton jackets that would look great on a Bonneville. A few brands to check out are Belstaff, Roland Sands, and Merlin, among others. I believe Triumph may offer some as well. I have a motorcycle buddy who rides a T120 and wears a Belstaff. Classic.
Leather always looks cool and is a good traditional choice for a Bonneville (if the right style). Waxed cotton jackets are good - I have a Merlin one - but have also worn textile (just don't have a Bonneville anymore!)
Whichever flicks your switch mate, what I like shouldn't influence what you like (unless it's in the form of a review of course). Get whatever takes your fancy.
I have the Outlast jacket, which is the short version, no belt as I'm not particularly keen on that look. Had it about 18 months now and am impressed with the quality. Its warm enough to wear in winter as the quilted lining is very effective and whilst it's not fully waterproof it's better than my Triumph textile jacket.
I love my Roland Sands waxed cotton perforated jacket for the summer. Helps keep you dry if you get hit by a short sprinkle and with enough ventilation to keep you cool on all but the hottest days. The styling hits all the notes for me when I'm tooling around town. https://rolandsands.com/truman-jacket/
For me it has to be mesh in the summer, but it is definitely leather in the winter. I have several and the one I will favor for riding the bonnie is my leather "Fonzie" style jacket. I think they look good together.
I’d love a Belstaff Brooklands leather jacket in dark brown. I think they’re super cool but goodness me, they’re £1,000 Still, you can’t take it with you
So, David, I would say that the solution is simply to collect several motorcycle jackets. Then you can choose what you wear each time you ride by temperature, precipitation, and mood!
Style, Protection, both? Leather is mandated on track for good reasons. Cordura and Ballistic nylon will withstand abrasions and tears, but will not slide as well as leather. Protective inserts and back protectors are important. That old bomber jacket may look really cool, but the soft leather won't last but a few feet on the concrete. It is clearly your choice and your skin, so no judgement. Just know what you want and why.
"The more the better!" How did you know my personal motto when it comes to motorcycle jackets, @JtC?! I lost track of how many I have so I went to the closet to do a count. Hmmm, I'm embarrassed to say that it's in the double digits! But that's ok. I never stay embarrassed for long. I have a variety of types from a variety of manufacturers--leather, textile, mesh, and waxed cotton. Harley-Davidson, Joe Rocket, Roland Sands, First Gear, Spidi, and Speed & Strength. I always tell Mr. Sandi that at least I don't collect antique furniture, classic cars, or airplanes. I do actually wear all of my jackets, though some more than others. Of all the motorcycle jackets I own, I only have one for which I paid full price, a beautiful Oxblood Red Roland Sands leather jacket that's one of my faves.
Depends on the weather here. 96% humidity and 90F means mesh . When it cools down to 80F I switch to a perf leather , and full leather below 60F
Personally i look at it this way, everybody says leather is safer, slides better and is more abrasion resistant. On our narrow uk roads that we all love i think sliding far is the least of your worries, lamp posts, walls, other vehicles are far more likely stop you sliding before you wear through most decent bike gear whatever the construction. Wear what you feel comfortable with and in. I will wear either leather or textile depending on the circumstances, weather, duration of ride, where i'm headed to, what i will be doing when i get there. As @Sandi T. says you can never have too much gear.