Altus is synthetic insulation, not down. It won’t be quite as warm, gram for gram, as a down jacket. If you don’t know the difference, I’d probably get a synthetic. It’s slim fit (quite handy if it is going under a waterproof). It doesn’t have a hood (If it’s for keeping warm, a hood is a good idea).
Nimbus is the Altus with a hood, but also has a boxier cut.
Nebula is very similar to the above, but slightly more insulation, so a bit bulkier and a bit warmer.
All nice jackets. Choice between them really depends on how warm you want it to be, fit, and if you want a hood.
I like Rab kit, so if you aren’t using it in the mountains, and just want to pose in it, why not go for something much cheaper that will do the same job? This should fit in with your policy to be less materialistic? Or has that completely gone out the window :-)?
