I would say that Hafler at least touches the "nice" threshold... TransNova being "nicer" than the TA series.
There's a lot to choose from... Me? I'm a Bryston guy... Even used (they come with a 20-year warranty, so finding used ones with several years left is pretty common). "Audiophile" (I hate buzzwords - even when they're the truth) grade, hand assembled, HOT running (class A, A/B), headroom for days.
Hooking one up to some decent speakers is an ear-opening experience - If you hook up both amps and then one channel to one amp at a time.
Before my old Bryston came in, I was "between amps" for a couple weeks. I was using an old Kenwood (the expensive, nice, "audiophile" grade Kenwood) amp until the Bryston arrived. I thought it sounded "okay" until I hooked up one chanel on the Bryston...
Everything was so skewed sounding... It sounded like I had a woofer and a tweeter on the right (Bryston) and a mid driver on the left (Kenwood). Flipping back-and-forth on the L/R was really something...
Moral of the story - Don't skimp on your monitoring chain. You can't tweak what you can't hear.