I've use Fairtex, Twins and Top King. By far the best is Top King. I love the fit of the glove compared to Fairtex, which I've been using for a little under two years. I switched over to try Top King and I love them.
For sparring, especially if you are doing MT sparring, TK are much better. They have more padding on the back of the wrist compared to Boon(from what I've seen at my local gym) and from Fairtex(from my own personal use. The wirst support is also much better. Inside of the glove is very snug, but not too tight if you want to use wraps, which I always use.
I'd recommend TK. They are harder to get in the US, especially since most dealers are in Thailand(except for a few, including the site I bought out of) and they are harder to deal with.
I actually recently bought my Top King gloves from a US dealer that has in stock in the US, as opposed to most other sites that have their stuff in Thailand, which is harder to get. I bought off themmagarage.com. Its a smaller site but their service was awesome. I had emailed the guy for questions regarding other stuff and he mentioned he had Top King in stock, but not on the site yet. I was able to convince him to let a pair go before the went up on the site. Great price as well. Maybe he'll do the same for you? lol
I was just about to post a thread on the recent stuff I bought off them.