We advise you to book your trip via trekking company of course. But this recommendation is not biased because we are one of the trekking companies in Nepal. Unless you know someone who is professional trekking guide in Nepal, your first choice should always be joining with a registered company.
The main reason we are recommending you to book your adventures in Nepal via trekking company is that a company will help you arrange everything from your required permits to documents, your transportation drive to flights, porters to guides, your lodges on the trails to assist during your emergency helicopter operation in contingency situations. After all a trekking company with good connections are always good things to have especially during these tight situations like flight delay, cancelled and all. Full in-depth information and facilities are provided by the trekking company with full responsibility while its difficult to trust a single person. Mostly trekking companies in Nepal uses local porter and local guides, so it will also affect the local economy in a positive way directly.
On the other hand, you also have an option to join Nepal trips by hiring a local guide on the spot at starting point of the trek. But the risk is higher over there unless you already know him. You have to constantly negotiate with him for his day rate, his lodging and fooding along with other services. He might not show up, not government licensed or even not been to that place before, which never happens if you are with good trekking company. Also you will not be clear about price includes and excludes as he might overcharge you. Sometimes, trip cost might come down a bit, but at what cost? You are trekking to have fun and adventure rather than focusing on other issues which are best handled by professionals.
In some situation, hiring a guide has been good but at most of the situation, getting professional services from reputed trekking company has been best. The choice is yours. Now if you are concerned about which trekking company to choose? Simple answer. Choose us, you will not regret, it will be your right decision instead.