I far prefer T-10 to regular Tanqueray, at least for martinis. I like a gutsy, in-your-face gin for martinis, one that will hold up to a bit of vermouth.
My very favorite gin is Anchor Distillery's Junipero, available only in California as far as I know. It is even bolder than T-10, but bother are well balanced and complex.
As much as I think they have a similar style, I remember tasting the two of them blind a few years ago and being surprised how different they were from one another. Can't remember how, though. I'll have to try that again.
Last evening we went out to dinner with friends and I saw a gin I'd heard about, Hendrick's. This Scottish gin is made with rose and cucumber as well as the usual juniper and other botanicals. I ordered a martini made with it, and while it was interesting, I don't think I'll bother again. A little too soft and perfumey.
There is a review of it here.