I am 240 so I have a larger problem than you. I have been riding 20m and 15m Waroo, but am looking to make a change. I am currently looking at the SS T3 17m, the Windwing Batwing 15.5m, and the 16m Thruster from Eclipse as my next large kite.
I have ridden a SS T2 14m and was blown away by the grunt that kite had. I have not ridden the Batwing yet, but the low end is renowned by those who have. The thruster is supposed to be a very fast kite that generates lots of pull. I am working on setting up a demo on one of those.
Most bowkites around 16-17m2 wouldnt be a bad choice if you want a tubekite. The new Cabrinha Crossbow IDS 16m2 would also suit you well. Myself only 67kg, so got the 13m2. If you are on a budget maybe a 2008 Contra 17m2 would be okay, but the Crossbow IDS got/should have the same range, and is faster with more responsive control.
Hey at 210 you're still tiny in my book... I'll echo the top two comments. A decent 16-17 meter bow / sle will probably be fine for anything you'll run into. I use my Bularoo 16 in almost anything and I weigh 245, but for those super light sessions I pump up the Waroo 20m. At your weight, I don't see much advantage to getting a 20. Other guys here swear by their Contras (they're all on 14's) .
IMO for this weight 14-15 sq m is enough if it is stable bow kite with deep profile, the flatter the better. bigger kites in these winds have difficulties to support itself in the air and they are more slower. or you may consider bigger foil e.g. silverarrow. as for speedy kites with low profile and low diameter tubes with week winds they don't have enough speed to create pull to move your heavier body. also latest delta shaped kites with same flat area have bigger projected area, so you might consider to use them for a change
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I'm 120 kg and Rhino '08 16m with an Underground 148 x 46 does me perfect in 12 to 15 knots. I still can go in 10 knots but your working the kite. IMHO below 10 knots and bowish kites are not fun anymore.