Definitely the 3.7i's. Awesome speaker, especially at its price point. I would consider pairing them with a Pass amp, something like a used X250.5 or the new 250.8 with 500wpc at 4 ohms. These amps have just a hint of warmth which I feel that the Maggies need. Maggies really shine the best with high power and high current. I run a Pass X250 with my 1.6's. A Mac 452 amp is another good choice. I have heard that combo with an ARC LS27 preamp and and Atma-Sphere MP3 preamp. Both sounded excellent.
If the 3.7i's are not in the budget, the 1.7i's are an excellent speaker. Pair them with a nice sealed sub or two like a Rhythmik and a good amp and they sound great.