FT have been excellent, been buying from them for a few years, excellent service.
Shipping does fluctuate, most orders within 10-14 days, others took about a month, one got lost for a few months. The biggest pain is when they have items that doesn't ship the next day that can cause some delays, sometimes quite bad ones, and the most annoying is when they end up not able to get something after all. Service is great but a bit slow to respond unless you can get a chat going, where they are able to fix most situation on the spot. They also offer an excellent warranty for most things and they do respect it. They do have specials and sale on many things and coupon on a regular basis.
The reason I used any other is that for such items that they don't carry anymore or don't have in stock (or simply don't have).
Gearbest is quite fine, but usually a bit more expensive.
I like that they have a fairly accurate system about their level of stock at hand.
I've just got a few things off Ali-Express, so my opinion is still pending as I've yet to receive anything at this time.
But out of several items, one tank has been a pain, as tried two sellers who turned out to not have it in stock as stated.