That's how you pay for quality. Long training times.
Hired troops are good, you can gear them up however you like and unlike any other infantry, they have guaranteed ranged weapons. They're somewhat easier to train than Kaikoth Guardsmen or any similar high quality infantry, like Valahir or Third Legion/Venetor troops, though unless you've got maxed surgery, they can be hard to keep in sufficient numbers.
Otherwise, Maccavian Northguards are good for the time they take to train, Hakkon Legionaires can also do quite well for their spamability. I've also heard good things in that regard about Cretasan Ironclads, but never used them myself, and Cretas recruits are limited.