Don't know about others, in terms of aural pleasure, they are nowhere near my Lenovo P2. A colleague owns that phone, he too was surprised (a wee bit disappointed) when he heard the volume in my P2 - OP5 is a terrific phone otherwise.
Just FYI, I own Lenovo Vibe X3 as well, P2 for me is louder than X3. Vibe X3 was charred by the poor software optimization and the buggy Marshmallow update which further led to the deterioration in sound quality via headphones. Hi-Fi doesn't work as expected in MM 6.0. Planning to flash a stock ROM just to get that sound quality back. So yeah, avoid X3 as well for now.