I did anti-clockwise in '22 and clockwise in '23, both have their pros & cons, but a few comments on what did / didn't like.
Clockwise.
1/ You'll hit the A82, Glen Coe and the run up to Fort William at the worst time, Saturday morning, middle of the tourist season. It was absolutely heaving with coaches, camper vans & tourists when I went through last year. Even on a motorbike opportunities to overtake were limited. I got lucky with a clear run alongside Loch Ness, but I can imagine it can be equally as bad.
2/ Dreghorn & Berwick are really just fuel stops, yes Dreghorn has a better shop, but neither have a sit down area if you need a proper rest. Loos are a bit naff as well.
3/ A9 & A1 South, you're on the home straight, the end's in sight. I found the scent of Squires dragging me along when I really should have stopped for a break. Also you need to be aware of the numerous speed cameras on the A1 when it's dark and you're weary.
Anti-Clockwise.
a/ You get your first two check points done fairly quickly and Wick is slightly less than half way so feel like you're pressing on which I found quite satisfying.
b/ Glen Coe and all will be quieter.
c/ M74 & M6, yes it's a drag, but both do have proper services, decent loos and somewhere to sit for a proper break if you need it. BUT, don't leave a food break to late into the evening. Many of the concessions close after a certain hour and there's little choice other than the usual prepacked rubbish.
Lastly, on both times I've avoided A82 alongside Loch Lomond and done the via Callander bypass route. You still potentially run into the camper van & tailback problem, but generally the route is a lot quieter so it's less of a problem than the Loch Lomond route. For other reasons the bypass route allows me to place a Poppy at the David Stirling Memorial which is quite fitting for the RBLR event.