I just bought my BenQ GL2450HM (not sure on the exact difference between that and the BenQ RL2455HM, but mine was £10 less than yours, so its very budget, and mines is 2ms response time to your 1ms) and I love it. Fantastic quality for what I paid for (i was upgrading from VGA, I was a bit behind), mine doesn't have adjustable height, but you can tilt it to face higher or lower which is useful. Onboard speakers are decent for onboard speakers, but I use my external speakers. Build quality is good, comes with all the features you'd expect, like being able to change light, contrast, audio, etc. I use mine for gaming mainly and it's great for that, so since yours is focused on being a gaming monitor, I can only imagine it performs even better.
I think there's a reason BenQ dominates for the cheaper monitor market, and I don't tend to see many bad reviews for their monitors. Hope you find what you're looking for