The Tango's advantage is that you can use it with all toys that have a hole for a standard-sized bullet (like Tantus vibrators, which come with some buzzy thingy that I find useless).
The Doxy might work as a massager (I say might, because my Bodywand Original feels awful to me).
That seems like two good reasons to eventually get both toys.
Though I want neither: I don't like hard plastic pin-point stimulations in a small package that numbs my fingers when holding it (the main reason why I hardly ever use the Tracy Cox "tulip" vibe - though it's nice that the bullet fits into the finger loop of this butt plug: http://www.lovehoney.co.uk/product.cfm?p=29779), and for me the big wands are not sex toys, but mood-killers...
I was thinking about the LH Desire, until I read the reviews about buzzy vibrations (I easily believe in buzzy vibrations but I'm wary of reviews claiming that a toy's vibrations are rumbly unless I know what the reviewer is comparing to: Do they even know what rumbly vibrations are? In my experience truly rumbly vibrators cost serious money.)
Now, my go-to clit vibes are: Firstly, the LH Venus Butterfly http://www.lovehoney.co.uk/product.cfm?p=22172 which objectively is a piece of crap (jelly rubber sleeve, straps don't work as they should and can be ripped off much too easily, not waterproof), but it's very powerful with the thick rubber providing the squishiness I love, works hands-free and takes rechargeable batteries. And can often enough be had for around £ 10.
Secondly, the Lelo Mona 2 http://www.lovehoney.co.uk/product.cfm?p=26151 which I got as a very good bargain (would never have paid full price!). I find the vibrations underwhelming (compared to the Denia), but the shape is easier to use for only clit stim (later penetration not excluded) than the L'Amourose Denia, which has the far superior vibrations.
G-Spot vibes also work as clit vibes, but normally it doesn't work the other way round, so I'll get more use out of a G-Spot vibe...
If I had to buy a G-Spot vibe at (nearly) full price, I'd go for either the We-Vibe Rave http://www.lovehoney.co.uk/product.cfm?p=34852 (purely on Dangerouslilly's recommendations) or the L'Amourose Prism http://www.lovehoney.co.uk/product.cfm?p=35385 (hoping/assuming that they use the same motors in all their toys). In practice I'll wait for the Christmas sale and see what crops up! It's only 7 months ;)
Oh, I nearly forgot to share Epiphora's classification of the Lelo Siri 2: She writes that it is more powerful than the JeJoue Mimi or the Wevibe Touch, but less powerful than the Mona. That means that for me both Mimi and Touch (and the Siri, which I had never considered anyway) are out of the running...