Triangle Competitors?

Audiokinesis or Classic Audio.

For American made, there are quite a few offerings that might fit what you're looking for:

Magnepan, Spatial Audio, Induction Dynamics, Vandersteen, McIntosh (?), Magico, Klipsch Heritage and JBL have been mentioned, already. 

fellow French hi-end speakers: JMR ,,,,  high efficiency and dynamic 

https://jm-reynaud.com

sample review

https://positive-feedback.com/Issue48/jmreynaud.htm

ZUs. Look good. Sound non-involving.

Same experience here with ZU.  I wanted to like them but nope

Zu room. Pillows on the floor spinning some discs, everybody was grooving but I wasn't. 

Me too, at friend's home with their flagship model. I was offering more of a caution than a recommendation. Check out Coincidents if you get a chance to hear them. Cheers,

Spencer

Should look at the Raven Audio speakers the CeLest Towers only $5000.00

My son has a pair and loves them.

Cornwall IV

I have not heard Cornwalls but I have spent a day with LaScalas. They are lively, maybe too much so. Very interesting.

Paradigm Personas

Thanx.

IMHE, the Zu speakers are quite polarizing.

I went to the first "The Show" in SoCal. Walked into the Zu room. Pillows on the floor spinning some discs, everybody was grooving but I wasn't. I sat in the sweet spot and just didn't get it. It might have been the source material it seemed very eclectic, but I didn't hear a hint of anything I might like but thanks for the suggestions. 

@chorus Thanks for the suggestions, I think they were very good. I might look at some Focals, perhaps very close to Triangle with in-house made pulp drivers just like Triangle. 

+ 1 for Paradigm

Cornwall IV's have been mentioned - they may fit the bill. There's also the active, lesser known Geithain RL901K speakers:

https://www.me-geithain.de/en/rl-901k2.html

How about Canadian?  I recently replaced my Triangles in one system with Paradigm Personas.  Similar high efficiency with that neutral, transparent, well integrated sound.  

Cornwall IV.

@russ69 A few I think of when I hear "lively"

• Coincident (Canada)
• Living Voice (UK)
• Zu Druid Series (USA) 

All are pretty easy to drive. 

IMHE, the Zu speakers are quite polarizing. I've been with groups of friends listening to them and some fall in love while others look like they're sucking on a lemon. While not my cup of tea, they certainly are lively, popular and come in tons of cool color options. Most threads rave about company support. Cheers,

Spencer

Have you heard Klipsch Heresy?

I have a factory custom pair of H3s in rosewood. Does that count? Nothing special sonically, just nostalgia. 

American made. Therein lies the rub.

USA

JBL 4367 Tower- USaudiomart $10k. Excellent Lively Sound for larger space.Horn.

Decware makes some Speakers of hi efficiency. Open baffle.

N. American

Paradigm Founders 120H $8.5k new. Best Seller in an SF HiFi store.

Heard with a $5k Luxmann INT. Sound was great. Piano, Sax.

UK

ATC-40's or 50s. Poor recordings won't go on these.

France

Focal Kanta 2s.Pretty Lively. Good Value Used.

I think you'd like the sound of B&W or Golden Ear, but easy to drive isn't often how I think of them.

Have you heard Klipsch Heresy?