I am wanting to get new hid low beams when I do my headlight retrofit. Need suggestions for which ones to get I was looking at the 6000k 35w hid but worried about brightness as higher temp less bright with hid .
Could consider led conversion kit.... But those are pricey...

Get a 6k 55w kit. It'll wash out and look like 5000k. Otherwise get 4300k 35w.

My 09M came with the standard 35w HID headlamps. I upgraded the bulbs to Osram CBH (cool blue hyper). These bulbs (with the factory 35w ballast) shine in a color that rivals Mercedes and illuminates whiter, wider, and farther than any other HID bulb I am aware of. They beat any HID bulb by a mile! The video below is my actual car, with factory 35w ballasts and the Osram CBH bulbs. Buy HID kit and the bulbs from The Retrofit Source. They are one of very few places that obtain everything direct from the manufacturer to avoid most places who buy from middlemen and send you excellently copied, low quality knock-offs.
I have Phillips DRLs mounted into my bumper. That is the first light you see in the video. Then I switch on the headlamps - you see the AFS system adjust for height and center as the bulbs go from blue-ish to broad daylight as they warm up. They never blind oncoming traffic as the cutoff is about as high as a door handle on nearby cars. Notice also that the beams stretch over 4 traffic lanes and reach very far in front with a balanced, white light.