Hi Edvardd,
Keep in mind this is all subjective & personal, depends what you're looking for besides 'naturally spacious soundstage' & the isolation, IEMs aside from hardware, eg driver tuning, number of, technical specs, all play a part in creating what we precieve & like in terms of sound...
Honestly, the only thing I can suggest is you have to decide yourself what you like &/or fits your requirements, no one can tell you what you like...or shouldn't.
The important thing is to have a quality source, at least CD quality, you know really well & just do demos, lots of demos.
Some I would suggest to start with are the following in no particular order :
Audio Technica E 70
iBasso IT 01
Meze 12 Classics
1more Quad Driver
Periodic Audio Beryllium
All the above have good characteristics for various reasons, whether they are suitable or what you are looking for all depends, as stated earlier, on personal preference, there are quite a few others which are possible but as I haven't demo them, it's hard to say.
Just remember to have fun.