Which of the following is the most common cause of tonsillitis in children -
"Acute tonsillitis usually occurs as a component of a widespread acute bacterial pharyngitis, usually due to hemolytic streptococci. The tonsils are swollen red due to mucosal hyperaemia and partly covered by creamy acute inflammatory exudate (acute parenchymatous tonsillitis). Sometimes there are scattered, creamy yellow spots on the surface (acute follicular tonsillitis) due to beads of pus extruding from the mouth of the infected epithelial-lined crypts".

From the above statement, it seems that acute parenchymatous tonsillitis is more common than follicular tonsillitis. But not sure.
It is worth noting that, overall most common type of acute tonsillitis is acute catarrhal/superficial tonsillitis as it is an early stage of upper respiratory tract infection and acute infectious viral fevers like measles and IMN. Most common cause of sore throat is viral, therefore acute catarrhal tonsillitis is the most common form.
Follicular
Atrophic
Hypertrophic
Parenchymatous