9m Naish pivot!!! + twin tip+North nugget
Seriously allround fun kite and would work for most things other than hardcore freestyle/ wake style, really good bottom end and also fun and controllable mega boosting top end. I have a 10m pivot (105kgs) which gets the most use of any of my kites, if I am heading to my local bump and jump/ flatwater spot ( woodies) I will just bring the pivot, nugget and the twin tip and this covers me for around 80% of the Perth summer seabreezes, it's also a lot of fun!
I'm Having a ball carving and doing little airs, nicely powered on the nugget at about 15knots and boosting big holding down the pivot up to about 28knots ( could probably go a little further either end of that range but I wouldn't bother as I have other gear) with the 2 boards this is not just the useable wind range but the enjoyable wind range.
Definitely adding a light wind directional like the nugget will add to your fun and massively increase your wind range of you just want to use one kite. But!! If you already have 3 kites just keep them and get more boards for more fun
The more toys the better 
Agree with the comments re one kite quiver, but if you are limited, consider a Zephyr 17 for the winds up to early 20s and then something smaller for above that like an 8 Edge or similar. The Zephyr has an amazing range - better than anything else I've ridden and takes the odd bigger gust well. Worth a test if you haven't flown one!
The other thing about not having a small kite is THE FEAR. It is nuking. It seems too windy for the kite you have. But the waves are awesome and you really really really want to go. So you rig up real slow, thinking to yourself the whole time "am I being stupid? is this the day I should just say no? am I going to get hurt? am I going to be that guy that gets the launch site shut down?". Then you stand around for a while humming and hawing, until you eventually are forced to make the choice: miss what could be an epic day (live to kite another day) or roll the dice and go for it?
On the other hand, when you have the small kite and know how to use it, you are STOKED and can't rig fast enough to get out there. All good! And yes, those nuke-ular days can be the best ever. This one's an easy sell to the missus....really is a safety concern! Plus, small kites are cheap.....people use them way less, so a few year old one virtually new can be had for peanuts. 
