Whichever model you decide to get, you cannot go wrong with it! I had both versions in my system for quite a long time and they are absolutely some of the best small speakers on the planet. Both are very well balanced, highly musical, with rich colors and refinement everywhere in the spectrum.
Both are excellent although with a little different strengths. I really can't say which is better; it would depend on your personal taste and the electronics you have. In my opinion the EAI has a little darker and thicker midrange (which particularly suits male vocals), a little more detailed and refined treble and is somewhat less dynamic. It does strings particularly well (actually, aside from Guarneri, I've never heard any truer textures to cello or violin). The EAII does not seem to be shelved down in the upper mids and therefore may sound a little bit brighter. The top end is very nice and smooth if a little less refined than that of the EAI. It's also a little more dynamic and the bass goes deeper.
Both are fairly easy to drive (nothing like the power hungry Extrema that can easily drain all the current even from a 350W beast - trust me, I've tried it!), however I wouldn't pair the EAI with any low-powered tube amps - it really needs some watts for the bass to gain the extra slam and extension. The EAII on the other can be matched with a wider variety of amps, either tube or solid state.
Both speakers have amazingly deep and dynamic bass that belies their size. No subwoofer would be necessary in a small to medium size rooms. In bigger space REL subs seem to be a particularly great match.
I hope this helps.