Repsol 4T Racing Synthetic 10W50, will switch to 10W40 next oil change for the winter.

10/40w Valovoline regular as much as I change oil can't beat the price(200-300miles).

I use Lucas High Performance Motorcycle Oil (semi-synthetic 10w-40).
Change the oil every 200-300 miles and filter.

Motul 5100. :D

Valvoline
 

20W-50 dino every 500.

I am a believer of using synthetic, but because I am so anal about changing my oil so frequently, I have been using either the Kawasaki dino motorcycle oil or the Honda brand motorcycle oil. I change my oil every 500-600 miles. Yes, its excessive, but I feel better doing it. On the sport street bikes I've owned in the past, I always ran synthetic (Bel-Ray EXP), and changed the oil every 800 miles. The reason I am changing it so often on my KLX is because of the intense Florida summer heat. Finally the temps are beginning to cool off.

Mobil1 10/40 here. I have used it in my cars for years, so why not the bike, too?

Just an FYI, You will gain nothing by switching to 40 Vs 50 for winter. With cold weather, the first number is the one that matters. If you want better cold weather flow, drop to a 5w. But you'll probably never need it that low. I would use 5w50 If Amsoil made it.
What is viscosity?
The first number, followed by W represents the low temperature viscosity, 5W, 10W, 15W... the lower this number, the more fluid at low temperature the oils, the easier the engine starts.

The second number gives the high temperature viscosity: 30, 40, 50. The higher this number, the more viscous the oil when hot.

Below are some examples on choosing car engine oil by expected outdoor temperature:

If lowest expected outdoor temperature is Typical SAE viscosity grades for passenger cars
0 degrees Celsius (32F)............................................. ... 5W30 10W30 10W40 20W50
-18 C (0F).............................................. ........................ 5W30 10W30 10W40
below -18 C................................................. .................. 5W30

Mobil1 Turbo Diesel Truck oil (its a synthetic) 5w40. Haven't seen it sold in 10-weight, which would be ideal. Been changing it ~1300 miles, or when it starts to get clunky to shift. Haven't been riding much trails which is why I've been going so long on changes. When the trails open back up it'll be closer to every 1000.

Please tell us you mean Mobil synthetic for motorcycles with wet wet clutches and not plain old mobil 1 car oil.