Hi,
I bought the Thermo system and for now I am happy with it.
Agilent do have 75% of the market share, but there is an explanation for that.
Agilent started selling low costs but rugged single quads equipment when Thermo sold only high cost high end equipment like Orbitraps or Triple quads. We can say they started from opposite positions. In the last years Agilent started to produce also high end equipment, where Thermo started to produce low cost equipment.
When Agilent started to sell, they made a HUGE discount and kept it for like 5 years. It was something like current ink jet printers (not the price), where they sell them just for the consumables. Same was in car industry with Volkswagen which means 'people's car'. They sold A LOT of beetles opposed to Ferrari, for example, that sold very few expesive cars. But as you can see lately Volkswagen started to make top notch cars also - see Bugatti Veyron... We are still waiting for Ferrari to sell cheap cars thou

...
After that they started to raise the prices but it was already too late for the others. 50% of the market was flooded with Agilent. From there, when you have 5 Agilents and you want a new one, you will buy Agilent because you don't want to mess with other consumables just for the one.
Indeed all the labs i visited had mostly Agilent inside. This didn't stopped me to buy a Thermo
Regards,
Vlad