Panniers - Ortlieb?

I've got a pair of Ortlieb Back Roller Classics that I use for commuting. I picked them up second hand a few years ago and they've been grand. But one of them has a hole on the bottom corner that I've not managed to patch. 

They don't owe me anything, so unless anyone has any foolproof patching suggestions I think they're due for replacement. 

Another set of exactly the same looks like the best option. Or is there anything else I should be looking at? I'd like a pair, at least 20l a side (needs to fit laptop, lunch, clothes), waterproof. Not fussed about loads of compartments, I'm happy to just chuck them in and I use a laptop sleeve.