IMO, they are very similar to each other...all rebloomers, all lace-caps...

I have tried both TnS and the let's dance rebloom lace-cap in my garden..I kept TnS, and the let's dance one was sent back to my grower friends...

TnS has the "lady in red" parentage, so it has better leave, stem colors in autumn (burgundy red last yr) - not bad in October when the last blooms are ready to fade...

i like the colors of TnS better, maybe just the ones I got...more vivid pink than the washout pinks over the let's dance plant...

what broke my tie with these two in favor of TnS was the let;s dance blooms turned to an ugly greenish plus leftover pink color as the blooms aged...some people may like that, I am just not a fan...

I have not seen summer lace in the mkts yet..so no idea there...

my thinking is all three are pretty much the same for most people...but if you are really into Hydrangeas' tiny details, I find the red stems, burgundy leaves in Oct, the more vivid pinks, and less ugly greening of the washout pink blooms more appealing and tipping my hand towards TnS.

One thing I notice the Forever and Ever series of Hydrangeas is they are very mildew prone...most hydrangea leaves get ugly in the late season - spots, wilts, brownings etc etc - and obviously powdery mildew problems...maybe the parentage of the F&E series, something makes them very PM prone...my blue heaven, and forever together turned into a powdery grey by October while the Endless Summers nearby have none of that/// just an issue to watchout for summer lace if mildew is an issue...

jmho.

Thanks so much tns does look pretty good...