As an entirely opinionated spectator to many of these teams, the hypothetical "best bhangra team" in North America would probably have to best NJW's raw energy, FCB's creativity and charisma, and SMD's execution and cleanliness. Many teams are fantastic, and the above teams are undoubtedly talented in many ways, but I have yet to watch a team that can consistently best any one of those teams in the corresponding benchmark I associated them with above. If you watch a competition with any of these teams competing, they rarely lose first place to anyone but each other, excluding the UK for now. Numbers don't lie. (See Burgh 2015, as they all placed!)
Teams that are pushing those boundaries in NA are NSG, with a solid list of recent placings most notably since BBC2014, Shaan Punjab Dee, with very impressive sets at Windy City and Chak De Bhangra 2015, and Vancity, with strong placings at Bruin 2015 and Idols 2015. Virsa OT and Furteelay Shokeen have had a history of strong performances as well, namely BBC2015 and 2014.
Ministry of Bhangra Chicago is also a very respectable matchup in the coed department, with consistent, clean, and a fairly creative take on the coed set. In recent past, Cornell, CMU, and UVA are collegiate teams that have demonstrated themselves to have high quality performances that rank alongside the above independent teams at their peak performance as well.
As for the UK, there seems to be 3 recent standouts amongst the rest - JVD, GCC, APPD (AJ, a personal favorite of mine, is also a close contender). In pursuit of direct comparison (considering my limited knowledge), I'd say that all of these teams possess a strong mix of the above three qualities, enough to put them up for "best team" against North America's finest. My gut feeling tells me JVD's cleanliness + energy edges the competition out. Would love to see GCC stack up against America after their fire performance at TBC2015, arguably a totally different type of set than their last one in America - which I believe was WBBC2013. APPD was probably the people's champ at WBBC2015 due to their unique performance and every Tom, Dick, and Harry fiending for their elusive mix, but I feel that their energy was outstripped by the other two teams mentioned(JVD winning WBBC2015 and GCC winning TBC can potentially attest to that).
Some honorable mentions might be SGPD & Joshiley Jawan, but it's probably better to factor them out due to inconsistent activity, despite their strong performances at Windy City and Elite 8 2015. It's hard to measure.
My personal top 8, for what it's worth, would probably be..
1. Josh Valaithian Da (UK)
2. Nachdi Jawani Warriors (Canada)
3. Gabru Chel Chabileh (UK)
4. First Class Bhangra (USA)
5. Shaan Mutiyaaran Di (USA)
6. Ankhile Putt Punjab De (UK)
7. Vancity Bhangra (Canada)
8. Nachde Shokeen Gabroo (USA)
One day far away, perhaps a brave group of souls shall overcome the logistical nightmare that would encompass bringing these 8 teams together for a monster of a competition...
Definitely let me know what you guys think, if you read the entire thing lol. This East Coast storm has me stuck inside, and I decided to write a little essay. I approached the question trying to answer it from an analytical perspective, and regurgitated a lot more thoughts than I was expecting. I hope this makes arguable sense!