I've used Twins, Thaismai, Everlast and Amber brand gloves. The first two were good, it's what I've seen most Thai guys use and share. The Twins and Thaismai were both good but the leather on the Twins was more robust. What I find most impressive is how comfortable they break in. Plus if you do stations like some gyms they are very fast to take off and put on...plus they're cheap and my stinginess can not be denied.
I like them a lot personally for the heavy bag because the form and design of the glove MAKES you have better technique. If you mess up or aren't paying attention it's much more evident. Maybe I'm over thinking it but there's a more tactile aspect to the gloves, you feel the whole process more then compared to running drills on the heavy bag with 10-14's. Also I have no fantasies of my punching power, I'll never hit the bag like Frazier, Foreman or Shavers-maybe when you get to that level of punching power you need the padding but for me I think the bag glove is adequate with wraps...
Wraps are mandatory though, for me at least I need the soft gauzy Le Roy's via a layer wrap across the knuckles and then another standard 180' cotton wrap the Thai way between the fingers. Both those wraps have technical names but I don't know them...Wrist support is non existent though so if you have wrist problems, I don't thank goodness *knock on wood*, you may need the popular training glove with a solid cuff.
I've only used bag gloves on the heavy/thai bag. On the double end bag I need the larger circumference to make up for my sub par skills and everyone else uses normal training gloves for the mitts so I don't deviate.
I've never seen anyone use any type of gloves on the speed bag...that's odd now that you mention it...
I've made a design for an old school bag glove with a longer cuff with bungee cord restraints so they are still easy to take on and off. In addition it would have an inner brace made of duralin plastic that would run parallel to the radial and ulna like the scales on a fish so as not to be obtrusive for added wrist support...