The new ERs are great. Mind, I'm in that minority of ER-4S people who just didn't like the ER-4P, so my likes are a poor proxy for yours. That said, I think ER2SE, ER3SE, and ER4SR all sound great, and I believe you wouldn't go wrong with any of them. I'm less qualified to comment on the XR models.I've had around 1/2 dozen ER4 sets since 2001 or so. First was ER4S and lasted me about 10 years. Subsequently I went to ER4P because I use them 75% of the time with portable players. My ears aren't shot but I do have tinnitus and ~50% attenuation 3khz and above. I don't presume to differentiate various headphones and long ago gave up audiophilia concerning speaker systems! I have some decent speakers, but will not entertain the notion of spending big bucks on upgrades.
I just sent two sets of ER4P's to Etymotic Research because they aren't functional anymore. I seem to get discontinuity issues nowadays not infrequently... I lasted ~10 years without such issues with that first set of ER4S. It seems like they don't make them to be as durable as they used to!
Unfortunately, I didn't seek warranty relief some months ago when at least one set (I think) was in warranty. Anyway, I expect they will suggest I get replacement sets from them at the discounted price they will offer me. They did this in June 2017, and IIRC it cost me around $150 for ER4P.
Should I just get more ER4P or maybe get one of the other offerings? I'm perplexed concerning the other ER4's available now. Suggestions? I listen to all manner of music, usually MP3's, but sometimes a CD player, also FM receiver at times, TV and Movies via DVD, Blu-ray and 4K player.
Out of the modern lineup, for someone who doesn't presume to differentiate various headphones and long ago gave up audiophilia I'd say try an ER2-SE and see how you like it – or an ER3-SE if the price difference is negligible to you. Either is just terrific sonically*, and I think you'll like the near weightlessness and easy replaceability of the new cable system in contrast to the legacy models'.
* For my tastes, I think ER3-SE is noticeably better than ER2-SE on good equipment, but not hugely so. Both will play nicely on portables, but on a less audiophile portable source I tend to like ER2-SE a bit more.