What is reccomended ? is some average stuff like Unibond silicone sealant ok, or is the premium stuff £9.99 stuff like dow cornering - mould resisant sealant worth going for? some of the £5 unibond ones state mould risistant, but a lot of people saying that dow cornering silicone stuff is worth paying an extra fiver for , for a 310ml cartridge?
is this all a marketing ploy ?
There are differences between silicone sealants and it's not just headline featureless such as mould resistance claims, but how good they are to apply and work with silicone tools. Unibond silicone is generally good, but I find Dow often has better adhesion and is better to apply/smooth and more durable.
However no one brand is the best in all categories so I use various brands based on experience. The only general recommendation is to avoid cheaper brands as although they can be good, its only using them and a long wait that will prove that.