I've used BitComet before and liked it. It went through a rough period (it was banned by many trackers due to the way it handled traffic, and it included adware), but the new version looks really good.
DHT is supported by all the main clients though, so that's nothing unique. Interestingly, there are two different versions of DHT, Azureus (Azureus) and Mainline (Bittorrent, Bitcomet, µTorrent, etc.) and unfortunately they're incompatible.
DHT only helps much on torrents without a tracker, which is rare.
DHT does not make you anonymous. Your ip address is in the open to be logged. You might eliminate some traffic from the tracker, but only if the torrent is running pure DHT and has no tracker at all, which never happens on purpose. Your address is still open to whoever connects to you, and your traffic is still being logged by your isp, etc.
There is a feature called Protocol Encryption, but that won't protect you either. Some people use a program called PeerGuardian for a degree of anonymity.
Usually, torrent speed will be the same for any client you use. Different clients get through your firewall and router in different ways. Bitcomet is supposed to be good at NAT traversal using UDP, so that could help if you're having trouble connecting at full speed. Fortunately I don't have to mess with that.
So it boils down to features and implementation as to your preference. For power users, it's either Azureus or µTorrent. For torrents with tens of thousands of files, µTorrent is preferred.