For me, there are two things that factor into an AEG.
1. Feel/Appearance. I'm extremely picky when it comes to rifles (I loathe all things AR), so being able to see the rifle on all sides and actually go into a storefront and hold it, shoulder it, wave it around (controlled, mind you), etc. is a huge plus. For times when that simply isn't an option, I research things like ergo, function placements (IE. Selectors, Releases, Grip Molds, etc.), and the like.
2. Loadout. Not so important early on, but once you settle in on a specific group you're going to try to impersonate, then you will definitely want a rifle used by said military group. However, since you said you'd rather not go too heads-in-deep right off the bat, this point is probably moot.
All in all, what it really comes down to, in my honest opinion, should be function over form. Find features you want/need (ambi selectors/mag release, STANAG-compatibility, Battery Capacity, Stock Features; like swing, underswing, retract, extend, etc; and a wide plethora of other options), then find a rifle that fits your mandate, make sure you think it looks pretty, and then narrow it down by researching different manufacturers, the ups and downs of all of them, compatibility/proprietary parts, and everything.
For me, intrinsic and in-depth research is key, along with getting a feel for the weapons platform.
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