To say that I'm a fan of gin would be an understatement. I'm a little hammered on it as I'm typing.
I mostly prefer London dry gin as a sipper, however the more botanical versions have made some interesting cocktails. Most notably the Copper Fox Vir-Gin when making a bloody Margret (Bloody Mary made with gin) and also Bo&Ivy Navy Strength Gin taken straight. As a former Navy man, the B&I is proper gin but is not for the uninitiated. Might want to strap up for this one.
Plymouth gin is a little different. Earthy really. Enjoyable to those who like a little "sweeter" gin with more root botanicals. Not very common anymore, but was the original gin in many cocktails.
Sloe Gin for elevens is a wonderful thing but bears no resemblance to London dry. I hope to have this once more during a hunt.
For a classic G&T...I'd prefer a London Dry like Beefeater (although my wife likes Tanqueray) with a fresh lime and tonic water. Want to take it to the next level? Muddle in a few mint leaves and the flavor will really POP! Wonderful on a hot summer day.