I mean I'm partial since it's my site, but I do like Beat That Flight - https://www.beatthatflight.com.au/ - in Australia/New Zealand (although you can use it anywhere, if that wasn't obvious) ;)

I find OTAs are often substantially cheaper, they make their money with upsells (insurance, txt updates, etc) but if you just tick no to everything, you can often get quite the bargain.