I am using a red 60 led 7443 tower bulb that is 5 years old. you can find these on ebay or amazon. I just bought some JDM Astar 2x "50W" bulbs (2.75 watts measured) that have a black aluminum body with fewer but higher power leds. I have not yet installed them.
the original 7443 bulb is 21 / 5 watts and emits about 440 lumens of white light. The lumens drops a lot depending on the density of the red lens (maybe down to 100 - 20 lumens) [I have not tested this lately] So a 1 watt red led would be roughly equivalent. So look for 2 to 5 watts to be brighter....
Now brighter is not better rather bigger (and more) is better. In the gloom of night we start judging distance by the size of things. When we look at the back of a car, it is how far apart the tail lights are that we use to judge distance. A motorcycle has a great disadvantage in that we are a single point of red light. If it is real bright but tiny, the guy behind you might think you are further away than you are....
So I have Red oval plastic red reflectors on the outside edges of my saddle bags as well as two red marker lights on the outside back edges of my rear crash bars to give the guy behind me a large double red triangle to help him judge his distance from me. Making the brake light twice as big (with this mod) is a very important improvement.
I also have a LIN-6 third brake light which I preferred over the TIR-3 and the hyperbrights because it is bigger! I run it at 50% power (4.8 watts) and the LIN-6 makes a wider beam so It is really less bright than the TIR-3.
Look at some of the new cars that are now on the road. When they hit their brakes their entire back end lights up. It really gets your attention.
Also note that many new cars have extra low mounted red reflectors. This creates a rectangle (with the tali lights) which gives you another dimension to judge distance with. They are also low because that's where your low beam is.....
Size and number matters.
Enjoy the ride.