For a first AP mount I think the EQ6R and CEM45 seem good options in that price range. I personally started with a Celestron AVX and recently moved to the Losmandy G11G (with the Gemini system). Maybe it’s just me but I don’t get any of the negative vibe from my Losmandy - the first time I set it up it was head and shoulders above any other mount I had used including some pier-mounted versions of higher end Celestron mounts. I think that any mount will be challenging as a leaner for AP because AP is more complex and exacting than visual astronomy (which in itself is not easy as hobbies go). All of my initial frustrations with the AVX were entirely me, not the mount - learning the process and techniques. Once I got the process down, only then could I bump up against the limitations of the mount. So get the best mount you can afford and be prepared for some frustrating nights followed by rewarding ones.
PS. I have never used an iOptron mount but at our last astronomy club meeting a member brought his new CEM60 and it looked very nice and solid to me. He had nothing but good things to say about it. So, some guy in Kentucky likes it, so what else do you need right?