Haneda is directly connected by both the Keikyu Line and Tokyo Monorail. Which is better depends on where in Tokyo you are going.
Keikyu
Keikyu is useful for routes toward Shinagawa and through-services beyond it. Check the actual train destination before boarding.
Tokyo Monorail
The monorail connects Haneda with Hamamatsucho, where travelers can transfer to JR lines.
Bus and taxi
Airport buses can be convenient for major hotels and districts; taxi can make sense late at night or with several travelers.
Choose by Tokyo destination, not by brand
Keikyu and the Tokyo Monorail both connect directly with Haneda, but they feed different parts of the Tokyo transport network. The useful choice depends on the hotel station and how many changes you would make with luggage. Airport buses and taxis can also be practical for destinations that are awkward by rail, especially late or with a group.
Sources and verification
Time-sensitive airport, airline, visa, security and transport details should always be confirmed with the relevant official source before travel.