If I can add my ten-Bob’s worth…
What you choose is up to you, but you need to think about the ‘what it’s’ before you make a final decision. Security, getting them on and off, weather, are you doing long trips or small trips, how much stuff you can get in, how easy is it to access your stuff, is access even an issue or the rack they will use and stuff like that.
I’ve got Shad 42’s on mine. They look good, they’re secure, robust and they do the job - but although I have enough storage space I find them a bit annoying because I have to take them off and lay them flat before I open them. Also, because theyre ‘contoured’ (bit oval), they’re not very efficient when packing. It takes me a while to juggle things about before the case will close. I’ve got inners for them and it’s okay if I’m travelling minimal, but if I’ve got a lot of gear then it’s easier not to use the inners.
What you choose is completely down to personal preferences. As for me, I very nearly went for soft panniers as because besides looking cool - and having the advantage of being pretty bullet proof if the bike falls over - they are also much cheaper than hard cases.
But at the last minute I changed my mind from soft to hard my when I had a moment of sudden lucidity. Someone was selling hard cases so I went the sensible route and got these 42’s because I can lock them closed and also lock them onto the bike, which is really handy when travelling. I also bought them second hand as I couldn’t afford a grand for the ones I really wanted - some big aluminium cases. For me personally, I want the aluminium rectangular top openers for the simple reason that I would be able to pack them more efficiently.
But, I haven’t got any spare dosh to waste on them when I already have perfectly good luggage carriers and seeing that I got these at a good price they’ll do for me.