The 75/2.8 E-II lens is excellent. It came after the MC lens and before the PE. I have both the E-II and PE 75's and haven't seen any difference, though they are not the same optically, as is sometimes claimed. The E-II is around 25 to 30% less expensive, though both are pretty cheap these days. The PE has half-stop detents, but myself I prefer full-stop detents, so for me that's not important. The E-II also has the full-metal construction of all the lenses before PE, but the use of plastic on PE lenses was so well done that I don't think it detracts.
About lens designations. There are three basic designations for ETR lenses: E, E-II and PE. MC stands for multi-coated and was not the actual series designation, but because the lenses say MC on them and not E, that became the default designation. It works OK because all MC lenses are E series. Bronica has claimed that the "MC" was eventually dropped from their E-series lenses, as multicoating had become nearly universal, but I have never seen a lens other than E-II or PE without MC on it. From what others have told me, only the 105/3.5 E lacked the MC designation.
About E lenses: The original lenses had silver front sections, and there was a basic assortment of five lenses. Later E lenses had black front sections and were optically different, and there were more: seven E prime lenses, two E-II primes, two E zooms made by Schneider, an E tilt/shift 55mm made by Schneider, and 2X teleconverter. The two E-II lenses were the 75/2.8 E-II and the 500/8 E-II.
Later lenses are all PE, except that Bronica offered both the 500/8 E-II and the newer 500/8 PE. The 500 PE was top-notch optically, but was much more expensive than the E-II (which was pretty expensive itself), so they offered both (kind of like Canon's "L" lenses and their regular lenses). There were some new focal lengths in the PE line including a fisheye, different zooms, plus a 1.4X teleconverter.
The MC lenses are still very good, other than the aforementioned original 75/2.8 with 58 mm filter thread and the 150/4.
In my experience I have seen little difference between the 150/3.5 MC and the 150/PE, except some flare reduction in the PE. I have both the MC and PE 40's, and while there is some improvement near the edges and somewhat less flare with the PE, I like the look of pictures from the 40 MC a lot.
So, what I'm saying is, the MC series is no slouch. If money is an issue, don't hesitate to buy MC instead of PE. They are considerably less expensive in most focal lengths. Especially for someone getting their feet wet to see if they like medium format, having the latest glass is not that important. I bought MC lenses (and a 75mm E-II) when I was just wanting to see if I liked 645 format or even medium format in general. If I had not gotten any PE lenses other than later lenses available only in PE, I still would have some really nice results.