OK, here goes. I have just found a bottle of martini in a clear out of the drinks cupboard. If I mix it with gin to make a martini will I be ostracised from polite society forever?
Bombay for me, then Tanquery. Not a massive difference imo though. Proper Schwepps tonic water makes a bigger difference than the difference between those two.
Opihr Gin (pr. op-here) is roughly in this same price bracket (I sell it at £23.99), it’s spicy so a bit different to all the others and worth a punt. Of the list I’d personally buy Bombay. If the choice was own brand / Gordon’s I’d recommend Beefeater, which is premium gin at entry level price.