Ive used all 3. Owned probably 50 Eminence Alpha 6s in different setups over the years, and now I have 16 Selenium 6s.
The Daytons are meh. I wouldnt use them for one of my builds. Not bad, but the others are much better.
The Eminence is great. Not much midbass, but screams. Take a ton of power. With the HPF set up around 125hz, it will take 200rms no problem. Loud as balls.
The Selenium is my personal favorite. Still very loud but they sound SOOOOO clean and have the most midbass out of any 6 Ive ever heard. I had a set of Hertz HSK 165s and went from them (4ohm) to a pair of Seleniums (8ohm). Direct drop in. Same doors (deadened and sealed to hell), same amp (MB Quart DSC4125), and all that. No tweeters with the Seleniums, just a mid in each door. Even with 1/2 the power (double impedance) the Seleniums are way louder and honestly, sound just as good if not better. Many people have told me this as well. Much fuller, bassier sound. With the 60w that I have to each I can change the crossovers on my 880PRS and play them FULL RANGE wide open. Literally not crossed over at all. They actually put out bass. Not midbass, but bass. They can get probably over 1/4" of excursion on some slowed down stuff. But just overall the sound is great. Its my new favorite speaker. I liked them so much I bought 16 of them. Soon they will all be in my truck.
I think if people on here could get over the stigma of "omg pro audioz soundz like p00p!!!!!111", and actually give them a real listen, it would be the new boner mid for sure. It kills a $400 set of Hertz comps no problems, and without a tweeter. Add a tweeter and it would sound even better.
Take the Seleniums hand down if youre woried about sacrificing a LITTLE output to get great sound and a ton of midbass.
Heres a video of them I took with my phone one day. This is no crossed over at all. Notice the deadener on the doors and how they are sealed. Without it, you wont get crap for midbass.