absolute, definite, main, major, real, undisputed (esp. BrE), undoubted (esp. BrE)
The real highlight of the trip for me was the visit to the Tower of London.

notable (esp. BrE)
obvious
personal
comic, football, musical, sporting (BrE), sports (AmE)
career
edited highlights (BrE), recorded highlights (BrE), video highlights
Recorded highlights of the game will be shown later tonight.
streamed video highlights from today's news

the highlight of the day, week, year, etc.
The highlight of the week was Saturday's fireworks.

clearly
These figures clearly highlight the difference in world living standards.

dramatically, graphically, starkly
The needs of these children were dramatically highlighted by the Action Group.

merely, only, simply
The talks merely highlighted the great gulf between the two sides.

particularly, specifically
rightly
repeatedly
recently

serve to
The incident has sadly only served to highlight the differences within the party.

Highlight is used with these nouns as the subject:
article, example, exhibit, report, result, study, survey

Highlight is used with these nouns as the object:
aspect, benefit, case, complexity, contrast, danger, difference, extent, fact, failing, flaw, gap, impact, importance, inadequacy, inconsistency, issue, limitation, link, necessity, need, peril, plight, point, problem, role, shortcoming, similarity, text, vulnerability, weakness