I'm not a fan of Optoma's cheap stuff as they have opted for a 2x color wheel with a clear segment to boost brightness claims, while delivering much weaker post-calibration brightness. Certainly as an entry level projector it gets incredibly good reviews from people who buy it and haven't seen anything else. But, it does do well, as most of their products do, after calibration because it is a decent product. The rub is that the BenQ models are better. For home theater, BenQ has opted for a 4x-6x RGB/RGB color wheel in what it offers. It reduces the rainbow effect and increases color saturation and post calibration brightness. In almost all cases where people have tried a cheap Optoma vs. BenQ, they have stuck with the BenQ projector over the Optoma. So, that would be my recommendation. Specifically, the HT1070 or HT2050 if that's in your price range. The HT1070 should be.
LCD is nice, for sure. The Epson models go brighter, no doubt. But, the DLP models will hit better black levels, and typically are sharper overall due to the single chip design. I would stick between the BenQ HT2050 and the Epson 2040 if I were buying entry level and those were what I could get. But, from a HD70, I would think that the HT1070 would be a solid choice. The HT1075 is an older model at this point and would not be my first choice from them.