Looking for the best laser cap: I've been losing hair for about 2 years

This is unlikely to give much improvement. I suggest seeing a hair loss expert now to evaluate and go over your condition and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone and/or hair transplantation. See an expert. Best, Dr. Emer

A lot of patients find the Capillus Laser cap to be very effective. It has 252 laser diodes. They have recently come out with the laser band which works wonders as well. It is a head band that gets all of the angles. While remaining very portable just like the laser cap. The laser band has 84 laser diodes and it is very effective. The laser is meant to re stimulate the hair follicles and manages to bring the baby hairs back to life. Both provide unbelievable results.   

There are many devices to supply this type of treatment but few of them really work for hair loss in a study I performed on two devices in my own practice.  A little over a five years ago, I agreed to work with a company that supplied Laser Hats to us at no charge (valued at $3,000 each). I got 12 volunteers and sold them a Laser Hat for $500 with the caveat that they would come into our office every three months for photos.  At the time we did this, we did not have the HAIRCHECK instrument.  It would have been the perfect tool to measure if any value was achieved with the once-a-day use of the Laser Hat. There were clearly problems in the quality of the photos and the way the patients combed their hair. I for one will admit that I was less than fastidious about standardizing the quality of the photos. None of the dozen patient reported any significant benefit. Four of the 12 did not come back for photos but I did speak to each of them a year later.  They were incentivized to get their $500 back and to keep the Laser Hat if they came in four times in a year. None of the patients had benefits from the laser treatment. 

I typically advise full light laser cap rather than the laser comb or wands.  Also, ideal wavelength to look for is in the 668-684 nm range, or even 830nm.  Best used for 20minutes at a time every other day.
Good luck!