To the OP, I can definitely recommend Kona Honu divers. I have dived with them on two occasions (this past summer and two years prior) and had excellent experiences both times. The first time, I only had a day in Kona and decided last minute to go on the manta dive if I could get a spot. After calling multiple outfits, they were the only one that still had a spot left. It was a great dive, mantas showed up in good numbers (8-10 if I recall correctly) and we were able to enjoy 50-55 minutes of bottom time in the circle before making our way back to the boat. Our guide Sandy was great and everything went smoothly.
This past July I was again in Kona for two days and decided to go on a couple of outings with them. Given my first good experience with them, I decided to use their services again, keeping also in mind that as mentioned upthread, their prices were slightly lower than some other shops for the dives I wanted to do, coupled to the fact they offered free nitrox, so I really didn't have any reason to look elsewhere.
I booked two trips: one night 2 tank trip to see the mantas again, and another trip the next morning (not one of the advanced trips as I didn't have sufficient time, but the regular local charter). On the night dive, unfortunately, no mantas showed up and they had been absent for over a week already, and a lot of the divers on the boat were repeat divers from the prior days hoping for better luck. We ended up going for 2 60-minute night dives with Kevin, after waiting the usual 15 or so mins in the circle to see if they might show up. The dives were nice despite the disappointment of the no show, and the fact we were allowed to dive up to 60 min was pretty nice. The next morning is where I really had an outstanding experience though. This may or may not be relevant to you depending on your air consumption, but for me it made a ton of difference. Despite being a tall guy, I have a really low RMV, and was put in a group with a family of more recently certified divers (again, this was not an advanced boat). I ended up having the same DM as two years prior, Sandy. While the family of five I was diving with were pretty much all out of air at 30-35 min, Sandy dropped them off at the boat and took me back out to the reef alone, allowing me to get down to about 1000 psi on my ALU 80 before ascending. This obviously made a huge difference to the experience, as I ended up doing two 75-80 minute dives. On top of it, most of what we saw happened after the other divers had returned to the boat, including a tiger shark and a pod of spinner dolphins that came to join us twice on the dive! Needless to say, I'd have been pretty annoyed if forced to get back on the boat at 35-40 min with 2000+ psi in the tank, but fortunately that was not the case.
I can't comment as to other outfits which may also allow you to dive your air and also seem to have overall excellent reviews, but I certainly would have zero hesitation in diving with KH again.