Besides horribly cheap plastic bottle gin I can't really discern grades of gin. Couple that with the fact most people mix gin instead of drinking it straight like say whiskey, I usually just get beefeater as it is neither too expensive nor too cheap. It also has that nice juniper bite without being harsh. Damn, it's 8 am and you got me wanting a gin and Sprite
My wife drinks gin (Tom Collins) like it's her job. I buy Seagrams in the handle. Found that spending more than that resulted in no difference in flavor in mixed drinks.
There's a brand called Amsterdam or something like that, they make Vodka and Gin. Their Gin is really good and it's only ~$12 or something like that.
.