Tough call, chyamor, because each succeeds best at different things.
For customization? Moderntailor, no question--it's ALL customization; there aren't any "stock items" that I can see. Buying a shirt? Pick a fabric. Choose a collar (from a page of different collars in different heights; then choose collar lining, whether you want collar stays, contrasting color, etc). Choose cuffs (barrel? Round? French? Portofino?) Short or long sleeves? Inside fabric for collar/cuffs? Buttons? Pocket? Monogram? Placket? Split back? Darts? What bottom cut? That's REALLY nice in my opinion. Their prices are pretty good too. The only thing that gives me pause is that the fabric wasn't what I expected; otherwise I was really happy with the shirt and will definitely buy again.
For construction? I'd probably give the edge to Ravistailor, based purely on the items I got. The trousers look and feel great, same with the shirt. I'm not as crazy about the look of the jacket, but it's built well.
For ease of use? Indochino. You can look at the items they offer and pick one, and you'll basically get that. I'm not as crazy about the look and feel of what I got, but then what I ordered from them was more basic officewear rather than a suit.
Of the three, my next planned purchases will be from Moderntailor (after getting some fabric swatches from them so I'm clearer on what I'm getting), and the reason for that is that I'm learning about customization and what features I want in a shirt/trouser/suit. As a result, I'm going to try different things and anticipate some failures. By and large, I'm okay with that, and my mindset loves modular customization, so that's my interest.
If a Ravis traveling tailor came nearby again, I'd probably order from them again; the traveling tailor has complete swatches and can discuss your order, and the interaction is good.
Harder call on Indochino. I think if I wasn't so interested in customization I'd be more tempted; they have predesigned suits that almost certainly look pretty good without much effort from the buyer, and the stuff I got from them certainly wasn't bad by any stretch.
I still have to try Black Label (
http://www.blacklapel.com); I've heard good things about them and their website looks as professional and easy to use as Indochino.