I’ve recently got into 4a and I’d say that both the skyhawk and flight are great 4a yoyos.
I got a rextreme a while back but they are pretty flimsy and I didn’t care for the shape in the hand, but then again it broke quite a while ago so I don’t remember it that well. I had the first version rextreme and it had an issue with the axle spinning freely and the yoyo wasn’t able to be unscrewed. I don’t know if this has been fixed yet in the newer versions, but it left a bad taste in my mouth.
As for the skyhawk, is has taken quite a beating from me, still playing strong and I like the feel of it in the hand. I’m impartial to the bearing seat because it didn’t allow me use flowable silicone when the stock response fell out, not a big deal, but it might be fun to fiddle with if you have an extra A size bearing laying around. I use this one the most because I’m waiting to use the flight when I get a little better. I like the idea of having one beater and one looking a little better for now.
The flight is also great. The skyhawk was had a bit of vibe out of the package, but the flight has pretty minimal plastic vibe. As for play, the flight seems lighter, both are pretty stable, both have decent spin time. It’s hard to say because like I said I’m just starting. The flight is fingerspinable and the skyhawk is not.(Not that I know from personal experience)
For me I really like the skyhawk because it revived my interest in 4a after breaking my rextreme over a year ago. But the flight and skyhawk are probably around the same level of play as far as I know. Either will get you going and are very reasonably priced.
Hope this helps!