Well, if you're only going to replace the stock H4 bulbs with aftermarket bulbs, many forum members use the Silvania Silverstars - I've got about 36K on my current set, some members have had poor duration out of these, but I've done well with them. Still running my first set, replacement set in my spares kit.
These are what I would use. Available at most auto parts stores. This would be the most 'bang for the buck ' upgrade. About $40 to $50 per set. $
There are "off road use only" bulbs available that are increased wattage, ergo more light - but also more heat. Possible heat damage in the refectors. Possible overheating of the wiring. You might have to order from the UK to get these. $
An excellent aux lite install would be the Hella FF50's with Garauld's brackets - relatively low cost, and a good occasional use farkle. See here:
Gary's Post
Some forum members have done an HID conversion, changing the H4 bulbs to HID's with the associated hardware. Excellent amount of light and a reduction in wattage draw and desirable if you're riding a GenI bike and running any additional farkles. It is
highly recommended to have a spare bulb assembly with you if one burns out, as they're not readily available at the local Wally World.
And MANY forum members have installed aux lights, the current technology would be the Soltek Fuego or the PHID's. These are handy for vaporizing forest rats. And they draw fewer watts than the stock bulbs.
And have a cup of coffee, ok?