I have a 2006 Honda Rancher 420 - love it 99% of the time. I'm 6'3", 200lbs and do mostly trail riding with friends. I say 99% of the time because on rare occasions, I find the Rancher to lack the power to climb steep hills or hit the top speeds on the straights.

I'm debating upgrading to a Rincon - any thoughts on year or other brands I should be considering?

 

Problem with the Rincon is like all Honda Utilities it uses a lower revving ohv motor while everyone else including Honda on there sport ATVs use OHC motors, thats why Honda Utitly ATVs have the lowest hp rating per displacement. The big bore Rincon has only 39hp out of a 680cc thats what most mid bore 500 and 550 have in other brands.
Also the Rincon has a 3 speed full auto with no low range option. At least the Foreman and Ranchers have a 5 speed with super low 1st gear.

I ride with a 680 Rincon and it was only slightly faster then my 500 and it was beat soundly by a 660 Grizzly.
If speed and power is your thing in a 4wd Utility and you have 420 Rancher pretty well anything else would be a better choice.
Even Suzuki 500 KQ or 550 Grizzly would have much more power and speed also you get a low range and true AWD diff lock. Honda is the only brand left without a true 4wd set up of any kind.

When I traded my 450 Foreman for a 500 Polaris I only gained 50cc but I felt like I moved to a 700 and in low range it could also out pull the foreman and massacre it on straight roads in high range and the Polaris was 150lbs heavier.

And the ride comfort and traction difference,well that,s another long story...

 

Welcome

 

bang for buck go polaris. awesome power, great low range, AWD is awesome, and ride quality is the absolute best.

i have a polaris sportsman 500. I'm a big guy at 6'4" and 270 lbs and i ride double with my gf who's 5'7" and 110 and havent found a situation yet where the polaris felt underpowered. especially if i put it in LOW.

 

Welcome to the forums. Best power per cc goes to Can-Am. Best ride comfort with good power goes to Polaris. Yamaha Grizzly is a great all around machine, along with the Suzuki King Quad. Any of the 500 class machines will seriously outpull the Honda Foreman. I'd get a 700+ range if you want to go a bit faster than that.