The main alternative view regarding Leonidas and the Battle of Thermopylae is from Diodorus Siculus' work (11.8.4-11.10.4) who is said to be abbreviating the work of Ephorus, a 4th century BC historian (Ephorus was used by both Diodorus, Plutarch and other writers as a source).

There are instances in which the accounts are similar and differentiate, but Herodotus is the more complete narrative were as Diodorus only abbreviates the work of Ephoros. Herodotus refers to Epialtes as being the one to highlight the alternative route around the mountains (7.213) which is present in Ephoros' account (Diodorus Siculus. 11.8.4). And again, Herodotus refers to Persian deserters as having warned the Spartan camp (7.219) which is again present in Ephoros' account (Diodorus Siculus. 11.8.5). However, Herodotus states that the Spartans fought in the strait against the Persians (7.223) but the account of Ephoros references a night attack by the Spartans on the Persian camp (Diodorus Siculus. 11.10).

Plutarch dismisses Herodotus version as downplaying the bravery of Leonidas (On the malice of Herodotus. 32) and reaffirms the version referenced by Ephorus. Writers such as Gnaeus Pompeius Trogus (as referenced in Justinus' epitome of his work (2.11.15-18)) also echo the view of Ephorus as there being a night attack.

Flowers suggests that Ephorus version of events may have been sourced from a poem of Simondes - the whole article is worth a read (Flower, M.A. (1998), 'Simonides, Ephorus, and Herodotus on the Battle of Thermopylae', The Classical Quarterly 48: 365-379).

Which is the true (or truer) account is not for me to say, both accounts make reference to the usage of arrows and javelins which is corroborated by archaeological evidence.

You will also find the sayings of Leonidas in Plutarch's Sayings of Spartans. In terms of primary sources, Herodotus is really the only one that provides a longer narrative rather than simple references to his name here and there.