Bruckner is/has been/was a challenge for me.
It took me some time to get really into Mahler symphonies, but the real challenge there was just the length, I feel, just getting my head around an 80-90 minute symphony, especially as early in my 'learn about classical music' efforts as it was, but I really love his stuff now. While he certainly has an overall style, each piece is so strikingly individual, each symphony very much has its own personality and identity, for better or for worse (I love them all, but I can see how some wouldn't).
I say this being far less familiar with Bruckner than I should be (far less familiar with him than Mahler for sure), but my overall impression is that he wrote the same symphony nine times (or like... 10 and 3/4 times if you count the study symphony and the retracted one, and 9 being incomplete). I say that knowing full well that they're not the same, but my impression is that they're much more the same than Mahler's output, which isn't to say that the latter's are better or right, but that it's why they were captivating and easy to identify and remember.
It took lots and lots and lots of effort last year to really begin to 'get' his fourth, but it was suggested (along with the seventh) as a good place to start. I listened to recording after recording after recording over and over and over again to start to get it, and it only got to feel emotionally significant when I was already quite familiar with it.
It's puzzling to me what doesn't 'click' with me for Bruckner. I love the scherzos of his first and third symphonies, and the first movement of no. 1 is quite captivating, at least the opening. I'm familiar-ish with the ninth, and it's enjoyable, but it is taking me a long time to warm up to him, and I have been trying really hard.
That all being said, I bought a ticket last night to hear his eighth here at the end of may and am looking very forward to it.