If it is your first time in Montenegro, stay in Budva town and stop overthinking it. The centre puts everything the riviera is known for within walking distance: the walled Old Town, the long sweep of Slovenska Plaža, the marina, and the densest concentration of restaurants, bars and nightlife on the coast.
The practical case is choice. Budva has more accommodation than anywhere else on the riviera, from budget rooms and apartment rentals to full resort hotels, so every budget finds a bed here, and last-minute options exist even in summer, at a price. It is also the transport hub: buses along the coast and to the interior leave from here, which matters if you are day-tripping to Kotor or Cetinje without a car.
The honest trade-off is noise and crowds. In July and August the centre runs late and loud, the beaches are packed, and traffic crawls. If your priorities are quiet mornings and a book on a sunbed, look one headland east at Bečići or Rafailovići and commute to the town’s attractions instead.
Within town, the closer you sleep to the Old Town, the more atmosphere and the more night noise you get; a street or two back from the seafront buys meaningful quiet. Sleep central for the full Budva experience, and use the coastal paths and buses for everything else.