Determining the best cab or taxi service in Haridwar can depend on various factors such as reliability, comfort, safety, pricing, and customer service. Here are some reputable options that are commonly regarded as reliable in Haridwar:

1. **Haridwar Taxi Services**: Haridwar Taxi Services is a well-known local taxi operator offering a range of vehicles including sedans, SUVs, and luxury cars. They provide both local transportation and outstation trips with experienced drivers.

2. **Goibibo Cab Services**: Goibibo, a popular online travel platform, offers cab booking services in Haridwar. You can book cabs for local sightseeing, airport transfers, and outstation journeys through their platform.

3. **Clear Car Rental**: Clear Car Rental is another reputable cab booking service operating in Haridwar. They provide various options including budget-friendly cabs, AC taxis, and luxury cars for both local and outstation travel.

4. **Ola Outstation**: While Ola might not have a significant presence in Haridwar for local rides, their Outstation service could be a viable option for long-distance travel. You can book AC cabs for outstation trips through the Ola app.

5. **Local Travel Agencies**: Several local travel agencies in Haridwar offer cab services for sightseeing tours, pilgrimage trips, and outstation travel. It's recommended to choose agencies with positive reviews and a good track record.

6. **Hotel Concierge Services**: If you're staying at a hotel in Haridwar, you can inquire about their in-house cab services. Many hotels offer transportation facilities for their guests, including airport transfers and local sightseeing tours.

Before booking a cab, make sure to compare prices, read customer reviews, and check the reputation of the service provider. It's also advisable to clarify any terms and conditions, such as cancellation policies and additional charges, before confirming your booking.